Bold prediction: Uncharted 4 will release Summer 2015. Horizon or The Last Guardian Winter 2015.

[Burek]

I predict that Sony will time the release of Uncharted 4 to coincide with Halo 5.

Both games will release the same week. The only exception is if another PS4 exclusive gets released around the same time (Horizon, Silent Hills if it's exclusive, something else...), they will then sandwich Halo, U4 a week before and the other week after Halo.