I don't think that they will be able to decommission all redundant sites by the end of the current quarter. Maybe they can decommission redundant sites whose leases end this quarter. But the question still remains. Will the Sprint subscribers it served be given full access to the T-Mobile Network or not? Will Boost subs be given full access to the T-Mobile network before Sprint subs?
That assumes that hey move over band 26 or replace it by band 12 or b71 (if you have a compatible phone) they move over band 25 spectrum and possibly add another RRH and move over B41 panels/RRHs or replace them with T-Mobile compatible panels/RRHs with b41/n41 MMIMO and give you access to them via a SIM swap or something. Roaming is not working real well right now since you have to lose coverage before it will switch you over.