Yep, it's inevitable, it's going to happen. The question was there with HGSS because FRLG could have just been a one-off, to celebrate the originals, and to bring all the Pokémon of previous generations in, which wasn't needed thanks to Diamond & Pearl. HGSS came to be pretty much because the fans & the creators wanted them to so much. II was the best generation, but it badly needed an update. RS aren't in need of it nearly as badly as they were, but it'd still be nice, and it'll go nicely with their ten year anniversary, assuming they come before the third instalment for BW.
RS need to be updated if for one thing only: I want to play through Hoenn with the physical/special split in effect. Sharpedo, poor, poor Sharpedo, such amazing stats that it couldn't use. But now Waterfall, Crunch, Ice Fang, Earthquake (granted, it's always had that), Zen Headbutt (once the inevitable tutors come, which will be present in RS remakes)...so much there...I want to be able to use it properly in the main story...
And so many more...Lunatone...Swampert...Breloom...my only request is that they switch poor Sceptile's attack stats...