Good points, I think that Longevity has already been achieved (mostly), albeit not intentionally.

Basically people want phones for 4 main task: Comms, GPS, Camera, and Web. The current crop of phones do that very well. I'll be honest with you, I just had to check what model phone I even have....turns out its an iPhone 11...

This is very analogous to the growth path of the PC desktop. It used to be (80s, 90s) that people upgraded desktops every few years. Articles used to be written highlighting the upcoming features of next years models which the public eagerly waited on...each new model seemed to bring massive capacity improvements that resulted in real-world benefits....then around mid 00's the real world benefits of any additional improvement stopped being meaningful: Does it send emails? Does it browse the web? Does it have a spreadsheet?

Phones are basically a solved problem and outside of a few niche usecases there is no real pressing need to upgrade. In fact I would go one step further and say you should basically buy used phones from here on out....a lightly used Phone (in which you've let someone else take the depreciation hit).