https://www.statista.com/chart/8348/smartphone-life-cycles-are-changing/
Is this why you have to pay monthly for a phone now instead of just buying it at the beginning of a contract? (I refuse to pay monthly. I buy a used phone on ebay. But then, I'm cheap.)
US cell providers quit subsidizing/bundling phones in contracts last year. IIRC, they (Verizon) said they were trying to move away from monthly financing of phones. I'm pretty sure that sticker shock re phone-hotness-du-jour is keeping a lot of phones in service longer. That, and phones are becoming commodity items now and it's harder to conjure up a compelling reason to buy.
This dovetails with your camera conversation. As technologies mature, people keep things longer and I see it over and over again in my own habits.
- not changing over phones pocket supercomputers very often, because there's not that much difference. Not that long ago, a two-year old phone pocket supercomputer couldn't run half the apps you want. I have an iPhone 5s and no desire whatsoever to upgrade.
- Cameras have evolved incrementally and that matters to pro photographers, but even the pros don't need to turn over their kit annually like a short time ago. As for me, I only use said iPhone at this point whereas not so long ago I tended to carry an SLR
- laptop sales are low partly because some people are mobile-only, but mostly because they last. My current laptop is over 5 years old. Out of curiosity, the other day I looked at the machine I would buy if I were to buy a Windows laptop now and the CPU benchmark was hardly different. So I just doubled the memory and have no intention of upgrading.
- Cars - average age of a car on the road in the US has been going up and up. It's now 11.5 years. http://www.thefiscaltimes.com/2015/07/29/Here-s-Why-Americans-Are-Keeping-Their-Cars-Longer-Ever
My cars are what I would have considered absolutely ancient once upon a time (back in Vermont as a kid, cars were typically rusted junk after 5 years of salted highways). But so far they run fine and I have no reason to "upgrade." This I expect to change wiht the shift to electric and self-driving cars, but it also has implications for things like carbon output - if trends continue, most cars bought this year will likely be still on the road in 2030, so there's absolutely no way to have a carbon-neutral transportation system by 2030. At least half of the energy used by the 2030 fleet will be locked in this year.
And so on.