Re: Forward thinking?
The problem that I see is that most early LTE phones lack native VoLTE support. They use 2G/3G for voice. So when those older networks all go dark, not only will all of the 3G-only phones go silent, but so will a good number of 4G phones unless the carrier includes a VoIP app that can work over LTE data.
My current phone for calls is a 3G feature phone and I have a smart phone for things like WhatsApp, Web surfing etc. So long as someone still produces a 4G feature phone with a removable battery it won't bother me. I need a battery life that last longer than two days on standby for calls and I don't want to have to carry an external battery. Hence why I have a feature phone, it doesn't need a touchscreen or the ability to stream music just the ability to make calls and send the odd text.