I remember once the Pokemon.com mailbag (which was never a reliable source of information) answered someone's question about whether there would ever be GSC remakes. The answer was no. After RSE made certain pokemon unobtainable, RBY remakes allowed for many pokemon that were otherwise not obtainable in-game to be once again obtainable. I hear some people saying that there's backwards compatibility, remakes are no longer likely.
But think: what are the real reasons for making remakes? We see on the 3DS many remakes for games, such as Ocarina of Time, Starfox 64, and so forth. Why are these games being remade? Because Nintendo believes fans want to re-experience these old games. And they're right; remakes in general have sold pretty well.
Think about how old the GBA has gotten compared to the 3DS's technology. Think about how many new fans of the series, who joined at the DS era, who have not experienced Hoenn or even KANTO* for that matter. Think about the money Gamefreak could milk from this, and based on both the increasing sales of pokemon games and the profit reaped from remakes in general, they would make profit. Would the fans complain? For the most part, I don't think so.
I remember when Pokemon announced there would be big news, some people speculated either a 6th generation or RSE remakes. I correctly predicted 6th gen, because:
(1) It wouldn't make sense for pokemon game's debut region in the 3DS to be a remake as opposed to a new region, that could show their best use of the new 3DS features.
(2) There's absolutely no way Gamefreak would design another game for the old DS when Black/White was released when the 3DS was already out there. The DS held the longest era of pokemon, compared to GB/GBA.
Gameboy (1st) --> GBC (2nd) --> GBA (3rd, 1st gen remakes) --> DS (2nd gen remakes) --> 3DS (my predicted location for 3rd gen remakes.)
*I put an asterisk next to Kanto because I predict another 1st gen remake before a 4th gen remake, because FRLG is older than DPPt.