Even if official support isn’t possible past a certain point (Google and Samsung are pushing 7+ years, fwiw), all phones need to have a bootloader unlock mechanism for unofficial support past that point. LineageOS or mobile Linux with some broken functionality is still better than nothing.
Friendly reminder that we have already identified and largely fixed a climate change problem, the depletion of the Ozone layer, and we can fix other problems too:
https://en.wikipedia.org/wiki/Ozone_depletion