Not the user you responded to but in my case nothing. My Xperia 10 III is still working well after three years so there no reason to buy a new one.
Okay, I might be out of the OS support window so I might want to do see how AOSP does on my phone. But hardware-wise there's really no reason to upgrade (and much less to a comically expensive device like in the video).
The next couple years will be interesting. They can't just throw more processor speed at us and call it a day, so will be intriguing to see how they overcome that.
And neither do I. Currently running a (horror!) 2018 flagship on DivestOS. It's faster than anyone's phone that I know. Everyone is surprised at how fast my phone is.
I am enjoying it. Though it doesnt work on VoLTE when on LineageOS so i will not be able to call/text excrpt via wifi after April when 2G is shut down.
That may be the case for you, but it's still widely used for mobile card payment terminals, gps trackers, alarm systems and likely other applications that don't require a lot of data but do require strong signal and reliability
Nothing. My current average phone life-time is 7 years, and the majority were second-hand already.
I've spent under $400 a year on all my tech combined, including phones, tablets, desktops, laptops, accessories, toys, and anything else with a battery.
If you get good tools, you don't need to replace them.