I keep my devices for a long time. I’m currently using an iPhone 8 and have a 5 that sees daily use as well.
Now that Apple has switched to putting the newest chip in the 15 Pro and last years chip in the 15 would it be worth it to get the Pro when looking at using a phone for 6-8 years?
Don’t be silly. The difference in performance between the pro and no pro versions is negligible. They both will receive the same level of support.