Not like it's going to happen, but at this point I'd be happy with a Wreck It Ralph attraction and a Tron attraction. Swap out the Speedway with Sugar Rush (this also involves new, clean energy cars) and create a high tech Tron ride (though maybe not the Shanghai coaster). I guess the things that really bug me about the Shanghai Tron coaster is that a) it goes outside and b) it doesn't zap you into an arcade game.
I know that this would be yet another expensive queue, but it would be great if Disney could incorporate some sort of illusion to make it look like you are becoming a part of the game. Line the queue with arcade games, and when you scan your magic band, some sort of electric pulse takes you into the next section of the queue where there's lots of blacklight, projections of other Tron games, and Daft Punk. I don't really have a vision for the ride itself, other than it needs to be entirely indoors. Maybe they could put it where Buzz is now if the Speedway stays?