Or is savvy enough to do it or understand the process. Phones without VoLTE are going to be severely handicapped moving forward (which is a massive amount of Sprint users). Decommissioning Sprint towers means removing 1xRTT coverage (specifically, indoor coverage).
It's a bold move by T-Mobile. Especially since Verizon is also killing off CDMA in major urban areas, so there isn't any roaming to fallback on.
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?