Phones don't "die" because they no longer get software updates. They just become obsolete - as planned by the manufacturer. Sounds like the next step is to fix the software update issue!
Indeed, but the issue is that the phone manufacturer no longer supports the phone and release OS updates. And on Android, you could install unofficial mods to upgrade to a more recent version of the OS, but then some apps (banking apps for example) refuse to work because of... reasons, again making the phone unusable. And in a majority of cases, this has nothing to do with the hardware no longer being capable.