as Jarred says, there is no discussion if 4K will come or not. It will come.
It will come, but there is still plenty to discuss about whether it will stay. 3D came, 3D went again (as a consumer product).
That's not to say don't finish in 4K... But just because the people making 4K screens, projectors, cameras etc are saying that 4K is the next big thing, doesn't make it so (again, at a consumer level)