So this is a comment I wrote out to one of the questions asking about Frozen sequels and possible love interests for Elsa so I thought I would put it here too since I wrote so much lol.....
As for the sequel debate - I personally think that they should make a sequel though I agree with others that previous Disney sequels aren't so great. The difference for Frozen though is that the story doesn't feel finished (as evidenced by so many people clamoring for a sequel). Most previous Disney Princess movies were one shot - the big story was done and over with and the only thing to work with afterwards was somewhat less epic conflicts like how to fit in at the palace. Frozen almost has two main characters though (I know not technically but I think all the Elsa love proves she's not second fiddle to anyone). So there is more than enough charactarization and development to support another story (what else were we going to learn about Cinderella? Love the story, but it doesn't lead to any other obvious plots after it's done unless something totally new was introduced or brought back - they did that with Aladdin sequels and those are better than most). In order to make a good sequel, there has to be just as epic a plot as the original. This is often why sequel fail because writers tend to use the best plot first in movies for obvious reasons. However with Frozen, I don't personally feel like we've seen Elsa's greatest triumph yet - rather just the first amongst many more battles to come. She feels like a fantasy adventure character to me - this was the first book where the character discovers/comes to grips with their powers and begins to realize they have a bigger role to play in the universe. You can't tell me a snow queen is just going to be left to her own devices on her sweet little island for ever after. She's got some hella epic stories left to tell. So actually I would love to see a series ( a real one not just a cartoon about how today we have to find Olaf's missing nose again) - at the very least she has a trilogy in her. So it just depends on how they approach the sequel. Yes if they do some nasty nonsence where she's just dealing with everyday queen problems then it will suck balls no matter who the love interest is or what they do with the rest of it. If they actually come up with an amazing plot line though and keep the fantastic character development going (one of the biggest things Frozen has been praised for is Elsa's unique charactarization) than I would snap that box set up faster Anna on a redbull drink.
Now as for her love interest -- the reason so many of us (yes I'm team Hans for the moment though I could be persuaded to defect if a new character is intro'd lol) like him is because he has the potential to become an anti-hero ( or less formally know as the reformed bad boy). He could be the Snape of the Frozen world. It seems like he's doing horrible things but there is plenty of room for the possibility that there is more to his motivations than what we have seen so far. A very basic, right off the tip of the tongue, theory could be that he is being controlled by the evil mirror shard that is featured in the original fairy tale as infecting one of the main characters - there is a lot of mirror symbolism in the movie but technically no mention of the mirror yet so it is something that they could do a lot with for a plot in the second movie. Or we could deeper and more sinister (potentially a bit much for a Disney Princess movie) and go with the idea of him being forced to drastic measures for some reason - like maybe some dark and horrible villain that nobody knows about yet is threatening all these kingdoms and has forced Hans into his plans with threats against his older brothers (who he would do anything to keep them safe despite all the teasing growing up - gives another potential for some sibling love plot too). We've seen this done before with Megara - she only works and does terrible things because of her bargain with Hades to save her love (who turns out to be not so great thus her extreme bitter cynisism). I personally would love to see them take the character development momentum that they built in the first movie and roll with making Hans into a new member of the anti hero archetype. They have already set the stage for deeper meaning beyond the typical Disney formula of Good is good and bad is bad and there is no gray area because kids don't understand that stuff. Obviously Elsa's instant popularity proves that kids can love an imperfect heroine and probably benefit from it in the lesson that they will make mistakes but if they learn from them they can become the good person that they want to be. So Hans could possibly foster this lesson further (though I imagine they would probably stick with the mirror shard idea to keep the kids from getting too confused with the plot).
As for other possible love interests:
Olaf- What??? Nope, love the snowman but personally I feel like he is a child (has a child's mentality) and that would make Elsa a pervy perv in my mind so I can't get on board that train.
One of the other Brothers - Meh. Could be cute but only in a one of the famous shorts set to music kind of way. Unless they really created a stand out epic brother character, this seems like it would just devolve into a silly trite plot line no matter how you go about it.
Someone with similar powers (like Jack) - Again meh. This feels like it would be sliding back into the one dimensional relationships of Disney past ( "You're a prince! Whoa what a coinidink, I'm a Princess! We must be destined for each other!" "You have ice powers! Wow we'll be perfect for each other requardless of our individual personalities!") This is also the very kind of relationship that Frozen put down in the first place with the whole rediculous Han and Anna nonsense. I doubt that the same lady who told her sister that she can't marry a man she just met is not going to fall right into the arms of the first frosty guy she comes across.
Someone with opposite powers (I don't know? like the Flame Princess? lol) - Now we're talking rom com stereotypes ( "We're so opposite! Let the hilarity and lovemaking ensue!") But I do think this has some potential if said firey character had some awesome development (pretty much the only real requirement for a possible love interest of Elsa). It feels a little bit like beating me over the head with symbolism though if the guy (or girl - who knows, maybe Disney can be progressive) shoots flames everywhere and wears red all the time. I personally think if they went with this particular love interest, they should tone down the hotness (in flames not looks lol - been loving me some hot Disney princes here lately). They never did explain the troll crystals (is there a write up on this somewhere? - I've been looking) or there apparent heat despite Elsa's worst so maybe the character could have something to do with the lore behind that? Obviously not a troll but maybe some long sleeping Prince who was cursed with to be too warm forever and he's been powering the springs all along until he is awakened? I don't know just throwing some ideas out there.
Some character from another movie - as much as I love shipping there's obviously almost no chance of that other than maybe, teensy shot in heck here, of someone from one of the other CGs like Hiccup but other than brief cameos for fun, they shouldn't hijack people from their own epic story lines for the sake of one franchise. Though because of the way they left off Brave, I could see the slightest potential for a Merida / Elsa pairing but that's breaking too many rules too fast so that one will stay in the fan fic fantasies.
Of course Elsa doesn't need to have a love interest any way, I would be perfectly happy with a sequel that is sans engagement ring at the end. However, that being said, I do think that there would have to be some sort of new relationship to keep the plot fresh and interesting. The sister thing is awesome but now played out. They would have to either create a whole new conflict between the two (which feels like one of those annoying drama shows that just won't end because shit keeps happening and it's not satisfying) or they would run into the "life after ever after" doldroms of a plot line mentioned above. But Elsa has lived most of her life shutting herself off from everything and everyone, she's going to have problems relating to people that have nothing to do with Princess etiquette and if they follow the logical character development of it (only one dimensional characters are fixed with one great realization) then she would have problems with developing real friendships and they could make that into a subplot without having to go into love interest territory if they wanted to maintain her independence. This could play off of the whole alternate true love idea because their are definetly friendships out there that I feel would fit the bill for breaking curses. Plus, it would be fresh territory for a Disney Princess because as much as I love the sidekicks, Disney Princesses haven't really dealt with true friendship. Most of the sidekicks, if not all, are blissfully happy with thier princess and never question them or demand anything in return. They just exist to help the princess overcome her problems. So for me, Elsa would be a great place to start giving Princesses some friends (who would theoretically portray real needs and compromises) as opposed to just another yes man in a new animal's suit. Or they could just make a whole new Princess movie with that, I'm always game for more Princesses : D
TLDR version: It doesn't matter what they do with the sequel or love interest for Elsa as long as they continue their great story telling momentum from Frozen.