Nothing besides rumors which are not based in the slightest bit of fact. Hell, we aren't even sure if Gen VI will have eight gym leaders (likely will, but we can't be sure.) They might even turn Pokemon into an RPG-FPS for all we know.
The next games coming out are Black 2 and White 2, to which you can find out plenty of data on on this site.
After that, who knows. People are guessing the Hoenn remakes, but even that isn't a sure thing.
We probably won't see Gen VI for a year or two.