There's no doubt that they've always known that the GSC remakes would be made this gen, just like they already know there will be RSE remakes next gen. Pokemon is a massive cash cow, so why would they just throw money away?
It's way too close to platinum to announce the next DS games, though. My money is on the platinum update for Stadium. Hopefully it won't be anything like PBR, and we'll get an RPG mode, a decent friend-codeless online setup, storage like they had on the n64 games and updated 3D models. And by updated, i mean different, not just graphical touch-ups. Why do I have to deal with the same retarded gengar tongue thing after 2 generations of consoles?
I guess you can never be too sure - especially with those gold and silver orbs hanging above the soundstage - but Japanese companies are infamous for trolling the hell out of the populace.