Huh, there are many heroes and villains I want to see their childrens, but especially:
Jasmine & Aladdin: There is Jay, son of Jafar, so it can be interesting for that, especially if they've a son. And I really can imagine a son for them!
Rapunzel & Eugene: Not just because they're my favourite couple. I can imagine for them a son and a daughter, too, maybe an older boy, who would be more like Eugene, and a little naiv girl, like Rapunzel as their younger child.
Yzma: I want for her a badass son/daughter (maybe a son, but it doesn't matter), and as an antagonist!
Kenai & Nitta: Just because. :D And I would be really happy, if they make a chracter from an underrated movie like Brother Bear.
Meg & Hercules: I want a little Herc/Meg! Especially a son. But I can imagine for them a son sarcastic and sassy like Meg, or a son more like Hercules.
Tiana & Naveen: My second favourite couple! It's bad, because I can imagine for them a son like Naveen was before he met Tiana, but then he would be like Chad, and I don't want for Tiana and Naveen a son like Chad! But I can imagine a girl who's more like Tiana, and she would be fantastic!
Frollo: I know, I know... But I really can imagine he has a daughter! And yeah, he would bless her from the World and she would be distant, has no friends and be afraid from the world outside. Her father would be a real monster, but I can imagine, Frollo's daughter to became good later and realise her father wasn't right and that good she thought before. (Because just think about it: Frollo never thoght he is wrong. He always thought he is a rightious man, better than others. So he could tell this to her daughter, who could be that naive she could believe that.)
Ariel & Eric: And not Melody! Create a really new character.
Anna & Kristoff: A cute couple, and as someone wrote before, I can imagine him/her dating Rapunzel's and Eugene's son/daughter.
Shan Yu: Create a badass villain kid for the leader of the hun army who could fight with Lonnie!
Now that's all, but there are some other kids I can really imagine. (And there are some who can't appear, because their parents has kids in Descendants.)