It would be nice but I have my doubt based on nothing happening yet and based on how long NFL, and avatar are taking.
I'd be with you except for two factors.
1) Like we talked about in a different thread these plans take a while to bring a harvest. As a new CEO will be taking over (please let it Rasulo with his extensive P&R background) they're going to want to make bold bets to keep the company growing. They have to get started early for that to happen.
2) I know people around here are cynics (myself included) but I believe the executives at TDO know Pixar/SW Lands are simply not the right way to celebrate the 50th of MK. They are cool projects but the 50th without an MK addition would be a travesty. At the very least they'll put it through some serious renovations.
Wildcards-
If Tomorrowland Movie does well they could potentially fastback an E-Ticket for that park related to the movie.
Avatarland Bombs and Disney World attendance remains flat. Emergency investment in the tried and true MK would solve a lot of problems.