So recently I’ve been seeing the trend where Android OEMs such as Google, Samsung, etc. have been extending their software release times up to like five, six, and seven years after device release. Clearly, phone hardware has gotten to the point where it can support software for that long, and computers have been in that stage for a very long time. From what I can tell, the only OEM that does this currently might be Fairphone.
Edit: The battery is the thing that goes the fastest so manufacturers could just offer new batteries and that would solve a lot of the problem.
They could have always supported software for that long. They simply refused to.
There is no benefit to slowing the release cycle. All of the research gets done either way, all of the supply chain modifications get made either way, and as an individual you have no need to replace your phone every year. A multi-year release cycle does very little but screw over people who need a new phone during the wrong point in the release cycle, while also substantially complicating the supply chains by making demand much spikier.