For probably most people, other than those who just like to have the latest, these are the reasons that probably drive most upgrades from a still working phone:

For probably most people, other than those who just like to have the latest, these are the reasons that probably drive most upgrades from a still working phone: 1. They want more storage. 2. They want a wireless technology that their old phone lacks, such as 5G or newer WiFi or Bluetooth features. 3. They want a better camera. 4. They want a higher resolution screen. 5. They want longer battery life. 6. They want a different size. 7. They want different SIM options. 8. They want different biometrics. 9. They want more speed. 10. They want to get an OS upgrade and the OS upgrade requires a newer phone. 11. They want to get a new app and the new app requires a newer phone, or requires an OS that requires a newer phone. For many of these we are fast reaching or have reached the point where for most of us the phones already do everything we want in those areas. For instance for me personally: 1. Storage stopped being an issue long ago. My biggest use of storage was for my music library so I could listen at work. Even if I still worked in an office I would no longer need that much storage because most of what is in my library is also on Spotify. I only need my library for that handful of albums that are not on Spotify. 2. I can't recall running into a situation where I noticed cellular or WiFi on my phone was limiting me, on either my current iPhone X or my prior 6 plus. 4. Screen resolution in modern phones has long been above the limits of what my aging eyes can distinguish. 5. Battery life has been fine for me for a long time. That leaves these things that might get me to upgrade. First, there are these where I don't need to upgrade, but I would appreciate these things: 3. Better camera. Most of the time my iPhone X camera is fine, but I sometimes would like better autofocus, and the dark modes which were introduced not long after the iPhone X came out would be nice. 6. My iPhone X size is fine now, but as I get older and have more trouble with small print I might want a larger phone. 7. There have been times I would have appreciated dual SIMs. 8. I definitely prefer Face ID to Touch ID. Apparently I suck at hand drying, so for a minute or so after washing my hands I cannot unlock my iPad with Touch ID. If I was not already on a phone with Face ID this then might be a reason to upgrade. Second, there are these things that may make an upgrade necessary: 9. Speed. For the last 10+ years every computing device that I have upgraded because I need more speed has been due to the web getting too slow on the old device. I don't think websites have yet run out of ways to make their sites consume more processing power, so am expecting this to continue driving upgrades. 10. I'm fine with the features that have been in the OS for a while, but eventually an old OS stops getting security updates. 11. Similar to #10. Put it all together then these are by far the most likely reasons I'll upgrade: • I have to because of software (web gets too slow or security updates stop). • I want a better camera. There's a good chance that after I do upgrade from the iPhone X, the new camera will be good enough that only software will drive future upgrades.