Gamefreak is reluctant to release information on the new game, as well as new pokemon because there aren't new pokemon per say.
Sylveon is actually a fused pokemon (between eevee and audino), and that is the new gimmick for X and Y.
All "new" pokemon will actually just be fusions of pre-existing pokemon that you as the player must create.
The only catch to fusing pokemon is having the proper item to do so, and they must share a type.
B/W2 was just a precursor for experimenting with the fusion of pokemon, and the x/y theme relates to chromosomes/"splicing" together pokemon.