I'm only done based on what their new phones have. I buy through my carrier, who also handles much of the customer service needs and all of my warranty needs. I also don't care much about OS updates due to a history of them making changes I don't like. I'm on the V20 and not taking the Oreo update because nothing about it excites me. I know that mean missing out on future security updates, but I practice safe habits that make it not much of an issue as well.
So your concerns are non-issues for me. On the other hand, the V30 and V40 are hardware downgrades in many areas for me. Sealed batteries, glass bodies, OLED display, no IR Blaster, notches, etc. The minor spec bumps they have over the V20 are not worth the trade-off. By the same token, none of the current flagships offer what I want in a phone and non-flagships are not going to be as future proof, so I guess you could say I'm done with ALL manufacturers until they come out with something that meets most of my wants or the V20 gets so far behind that it becomes problematic to use (I.e. Laggy).