Yeah they could easily move it into Stage 17 or the former Hollywood and Dine building.
The speculation seems to be that Disney, much like they're doing with Epcot this year, considers this to be enough for DCA for now. So even though new Luigi's, Frozen show and new Soarin' doesn't any new capacity in any whatsoever, it's still three "new" attractions that gives them the rightaway to be able to ignore DCA for the next three years (at least) while they focus on Disneyland. Not to mention Food and Wine as well, which they will probably rely on heavily to get the spring crowds into DCA during that period too.
I mean, if they're going cheap they might as well add random drops on ToT like they've always wanted to. That along with a new World of Color could at least offset some crowds come 2019, so here's hoping they do something.