Modern games just last longer and they don't feel old even when they are. In 2000 if you played a game like Super Mario World (1990) it felt ancient. Today if you play Super Mario 3D World (2013) it feels still good and fresh. That's why today I feel pretty comfortable playing the current generation but also one or two generations behind at the same time.
That's a good point. Tech improvement is slowing down. The jump from SNES to N64 was big. Big in that you can see it. I mean if switch 2 is 1080p handheld mode at most people wouldn't bat an eye.