I have no idea what will happen to the third party stores. I guess location and volume should play a role or they could just let them all compete. Some of them could become Dish/Boost stores or Verizon/AT&T. There is sure to be some upheaval.
We also don't know what role Amazon will play in this scheme with respect to Dish. I could see them reselling Dish/Boost phones bundled with service. They cannot be a Dish MVNO during the 7 years while Dish is an MVNO of T-Mobile.