I feel like even though Unova is resembling Hoenn's features a lot (the stuff wombateiro just mentioned above) they're going to have to remake RSE eventually. They stopped making GBA games and Hoenn was part of the Pokemon history so they'll probably want the newer fans to experience it too. I don't think they're just going to.. forget about them.
When the GSC games turned 10 everyone was basically begging for a remake and we got one, though that might be because the games were 2 platforms old (Gameboy Color -> Advanced -> DS iirc).
Idk, I just feel like they're going to have to do it eventually, especially with lots of fans begging for a remake of these games, too.