If they make a third MI...

I always thought that at the end where sully walks through the door when you hear boo say kitty she sounds much older, I always thought the sequel would be that she grew up and wrote children's stories about her imaginary friends kitty and mike wazowski, and sully walking through the door would make her realize it was all true and she'd have kids of her own that would sneak into monsterland

Boo is now in high school and is a typical high school girl. She pretty much forgets everything about Sully and Mike, who now run Monster's, Inc as the co-presidents. Mike now has a wife and kids, something Sully now longs for. Feeling nostalgic, he tries to return to the human world to see Boo, only to get somehow stuck there.

In the human world, Sully meets previously banished monsters who reside in the sewers and still scare children simply out of sport (not knowing the new laughing-formula the monsters use) with Randall as the group's leader, who convinces Sully he has turned over a new leaf. However, unbeknownst to the group, Randall is also trying to find a new connection back to the monster world to extract his revenge. Sully also at first tries to find a way back for the banished monsters, but is soon sidetracked trying to reach Boo and get her to remember who he is.

I think that'd be kinda cool. :D

"Let the games begin."
-Bane, The Dark Knight Rises 2012