Microsoft already switched its release support to the "series" model. There are still big games coming out on PS4. With the PS6 expected to be very expensive, we may very well see games simultaneously released on the 4, 5, and 6. We may be moving away from discrete console generations. Older consoles still have a massive library you can cycle through as well.

Yeah, the console companies want to be profitable, but consumers are pushing for new stuff, too. I don't care a whole lot about graphics improvements, but going from HDDs to SSDs was a huge improvement and worth the upgrade for me. And software engineers as a whole have long favored requiring new hardware over optimization for current hardware. I hope the great electronics crunch will curtail that.