Your 8 realistically still has another 3 years minimum of use left in it. I have noticed that third party app support is generally good and will support iOS that’s 2+ years out of date. Even outdated apps seem to work. My Mini 1 on iOS 9 still runs a 5-6 year old version of Netflix which is fully supported.Your stretching the truth. The A16 will probably only get one more year of extra support over the A15. It is possible it will get 2 more years of support, but it is also possible it will stop receiving support at the same time as the A15.
Apple provides shockingly long software support for their phones. I bet the iPhone 14 and the A15 chip gets at least 5 more years of support, if not more. I am betting on more.
If the iPhone 14 doesn’t seem like good value to you, just get the iPhone SE3. It is half the price and will get the same number of years of software support as the iPhone 14. That is what I plan to get when my iPhone 8 gives out….although honestly my iPhone 8 and its 5 year old A11 still gets software updates and is plenty fast for what most people need from a phone.
The people who are moaning about longevity have zero intention of using an iPhone for 8-10 years. Even people who don’t care about phones tend to update within 4-5 years.
The original 6S and SE will realistically provide 2 further years of app support which will provide a total of 8-9 years of operational use. I don’t know anyone who would voluntarily use a 6S or SE in 2024.