I never really disliked the whole central dungeon idea. In Phantom Hourglass, I actually think it was a pretty nice challenge, bordering on overbearing (at least they had that portal to the middle, right?). I think a lot of people did find it overbearing, so when they re-used the idea in Spirit Tracks, they made it quite a bit more bearable. While seeing something like the Tower of Spirits appear in Skyward Sword wouldn't disappoint me, I highly doubt they're going to do it. The whole central dungeon idea is really a thing for the DS Zelda games. It wouldn't really fit in a Wii game. For that matter, though, I think we might never see it again, since there probably aren't many more DS games in general left to announce, and the 3DS isn't really made for 2D games (yes, PH and ST are 2D, even though the graphics are 3D and the boat/trains sections are 3D). That brings up the whole conflict of whether any 2D Zelda games will ever appear again on either console, but I won't get into that here.