If Sprint gets 4g lte working and keeps unlimited data that will be a selling point. There are also MVNOs working off their network and the upgrade will help there also. Rather have a customer use a third party MVNO on their network than go to Verizon or ATT. If Sprint network becomes better so do those cheaper MVNO's networks piggy backing on them.
Its already working. I took that on Monday.
Not nearly everywhere yet, most are still waiting. Now supposedly should have the vast majority or the upgrade done by the end of the year? So it is still a work in progress. The SoftBank cash is helping as would the merger.