It would be interesting to see contests return, and if they do, what kind they would be. I personally prefer the third generation contests over the fourth generation. (The dancing was the worst. XD)
To me, Goldenrod seems like a good location for them. It's a centralized location in Johto, as well as the biggest city, so there should be room enough for a building dedicated to contests. Celadon would be kind of late in the game, though, to me.
I don't really like contests, but it would be a good addition for those that like them.
Also, they weren't originally in G/S, so would they even be included in the remakes? They weren't in FR/LG, even though R/S/E with contests came out first. Which is why I'm interested in seeing how far these games will go as "remakes" and how far they go as "new games".