Ruby and Sapphire don't need remakes, since you can transfer your Pokemon from there to Gen IV, then to Gen V, and they don't look too dated, either.
What I want instead is prequels for them, in which the origins of Team Aqua and Magma rise to struggle with each other, and things about the past of Archie and Maxie come to light. It would be a rather interesting new direction, albeit with the same Pokemon R/S brought us with later-gen additions like Dusknoir and Rhyperior. I'd also think that they should definitely make Deoxys available in-game, possibly as a plot legendary.
Prequels would be a more intriguing way to go than a game that doesn't really need an update.