I was thinking about it today. I think the only reason we've had to say goodbye to Hiro and Baymax because Disney didn't have anywhere put them when they decided that they were going to close the Magic of Disney Animation. They can't go outside anywhere and really there aren't any good inside places to put them. So what if it's in the works to bring them back in a different location that will be better suited for them? All the way up until they closed, they had really long lines. The same happened with Anna and Elsa. They were supposed to be a temporary meet and greet (which is why they put in Epcot at first) then the lines grew, grew and grew some more until the Norway pavilion couldn't hold the line anymore which is why they were moved over to Princess Fairytale until they could further provide a better spot for them.
Basically my theory is that the Magic of Disney Animation was a temporary spot for them until they saw how well the meet and greet would do then possibly move them somewhere else.
What do you guys think?