I would hope, and hope is a strong word, that having multiple carriers (plus MVNOs) on the interchangeable LTE bands will encourage some competition that is sorely lacking due to incompatible frequency allocations.

Every spot in the US will be covered by 4 (5 is they ever find a buyer for the D block) licenses. In some locations, one carrier already has 2 of the licenses (e.g. VZW). I still see room for competitive behavior.

Why restrict yourself to the majors? The MVNO world seems to be where the real pricing competition is.