I don't really see a need for a remake for those games at this point. I haven't been able to play Black/White, so I can't speak for the Pokemon that we are missing, but for everything else.
Red/Blue (Green) got a remake probably because they were what started it all.
Gold/Silver desperately needed a remake seeing as the G/S/C cartridges' clock batteries were (and still are, my Crystal is going T_T) dying.
There's also the console convenience. However, I guess now the GBA games are no longer supported on the 3DS. I still have my original DS and I play GBA games on it all of the time. I have no need for a R/S remake myself. I feel like the first two were necessary, but at this point I don't feel like the rest of the Pokemon games need a remake.
And honestly, I don't know if I would buy it. I probably would, but right now I still need a working DS (preferably a 3DS =P) so I can play HeartGold and Black. They would probably fill the need of Pokemon games just fine for a long time. R/S were never my favorite, anyway. They'd have to make them better before I could go "I must have that!" at this point.