To 4G or not to 4G

A little background, A couple weeks ago my wife's Moto G5plus gave out, just went totaly dead at the tender age of 18 months.Went to Verizon,no help, local repair shop, no help. Took her old Droid Razr Maxx into Verizon to see if they would activate it so she would have time to decide the next move. Tech had to get permission from the Customer service gods to get it re activated as they no longer support the phone. We were told that many phones would no longer be supported and that soon everyone would have to have a new 5G phone.
Now the question, how much longer will 4G phones be supported in the mobile marketplace? Buy a new 4G LTE phone today or try to stretch the life of your current device. I'm still using, with no complaints, a Moto Droid Turbo and have every intention of holding out till a real 5G device is available but my wife needs to do something now. Verizon actually told us that her Razr Maxx would no longer be usable in a few months.
Thanks, JDH