All we need now is to make everyone wealthy enough to afford expensive audio gear and convince them that it's in their best interest to buy an $800 Schiit power amp that does not sound any better to them than a $150 Fosi amp.
I do not have any statistics on the average lifespan of Topping/Fosi/SMSL/etc. audio gear, but I would be shocked it was not far in excess of two years.
The usual market incentives are why we have this situation. While there is an upscale market for amps like the Vidar II, most consumers are more likely to buy something for $150 and then blow the $650 savings on things like food, rent/mortgage payments, clothes for the kids, and toilet paper.
I hope that you are right, because class D amps can reach 90% efficiency, making them four times less wasteful than 60% efficient class AB amps (10% waste vs. 40% waste). Class AB amps that act as space heaters doing battle with home air conditioners isn't ideal from an environmental standpoint (though it's a big step up over class A amps).