Not to be cynical, but I wouldn't plan a vacation around this ride. Not because I'm not looking forward to it, because I hate AE (not starting a debate, just giving my own personal opinion) and I love Stitch, so I'm hoping for the best, but in reality, this far in advance I wouldn't plan a trip around one ride that hasn't even been officially announced yet simply because with Disney's track record for opening things on time and on schedule, it's just not practical. Go, have a good time, and hope that the ride is open, but don't hold your breath for it, because my best guess judging from their recent history is that it will not be open till the next spring at best. And keep in mind, this ride has NOT been officially announced. I know I'm repeating myself, but TECHNICALLY the Stitch part of all of this is pure rumor, Disney has not released anything making that a definite...yet. Expect an announcement from them soon, however.
Again, sorry for being cynical, negative, etc...Just trying to give you a (somewhat) realistic idea of where things will stand based on an educated guess, as no "real" facts are available as of yet.