So has anyone released any concrete evidence that this stuff is real? I'm definitely remaining skeptical until there's something tangible to look at; when the demo was datamined, people almost immediately started ripping and uploading images, music, and text files.
That said, I was actually talking with my friend the other night, after he beat the game, about what exactly that Zack and Cloud alternate timeline thing could be, if that's what it is. And an "Episode Zack" occured to me -- essentially a parallel storyline that remixes the Midgar section of the game -- since they've already built Midgar. CC, not for Crisis Core, but for... Chronal Collision? Continuity Change?
That said, while I think redoing Crisis Core at this point, at least, would probably be a lot more difficult, once they've produced all the assets required for the main game, there's no reason not to just go for it and remake more stuff, or keep making new stuff set in the universe in general. FFVII, almost uniquely amongst the various Final Fantasy titles, stands out as a setting that really does warrant continued expansion.