Great Question. Since my amps are approaching the 10 year old mark, I look forward to the responses.
I think the OP is speaking of technical 'advances' in amp design and performance.
I think the answer is, there have been no advances. Just more of the same with a higher price tag. For the average person, reasonable priced high quality amps, are actually less available today, than a decade ago.
Soon, all we will have is Walmart's selection and the Pass Labs of the world.
He exempted class D.
Cheers