As long as Verizon continues to have good call quality.
It's amazing call quality. Same reliable coverage, just with better clarity (if you have ever used FaceTime Audio, it literally sounds the same, like they next to you). VoLTE of course only works in LTE areas, but on Verizon wherever you get LTE you get VoLTE. AT&T is still testing it in a few cities, but it should be out by the end of the year IIRC. (Someone correct me if I am wrong)