said by ISurfTooMuch:Who would fill what positions probably isn't settled, but I'll bet that Softbank knows which company would be the lead partner post-merger. Whether they've shared their vision with DT is likely dependent on what role, if any, DT would have post-merger.
Beyond the first part of NV Sprint has an upgrade path to Volte. The fiber and microwave being put in now has specs for later for easier upgrade to higher backhaul bandwidth.
Also the electronics had an easier Volte upgrade path.