And technically, Genesect in no way means all 649 are definitely in.
But the fact that no Pokemon has ever not been coded into one of the main games after its reveal means that there's no reason at all to think all 649 wouldn't be, even before the sixth gen was even announced!
Creator of Jay's Journey (see quote!) "It's not ten years old! Therefore, it sucks!" - Nostalgia whores everywhere