Who is going to finance such a large merger of Dish swallowing T-Mobile?
I am sure that Dish will ride on New T-Mobile's network for as long as they can. But New T-Mobile will not touch AWS-4. They will host AWS-3 and 600MHZ and continue hosting 800MHz but Dish needs to pony up for AWS-4 deployment whether they do it themselves or T-Mobile hosts it. I have no problem if they never develop their own network but there is a maximum of 5 years of being an MVNO per the merger agreement, I think, but that can be changed. I think that offering video on mobile devices for free if you join their network will attract the younger generation. Dish already has content licenses.
Lest we forget, the cable cos will be major players in the CBRS/C band spectrum. They can offload the rural/highway coverage to Verizon and use their own small cell based networks to service the rest. They can also play the video on mobile devices game since they have content agreements as well.