Technically, Platinum is already a remake. Its still Diamond/Pearl, but with a slight change in story, and changed features, but otherwise, its still the same game. Its the same case for Yellow, Crystal and Emerald. They're all remakes of the previous games in their arcs, with slight upgrades and changes. FireRed and LeafGreen were the first completely overhauled remakes. But in a sense, they're all remakes.