Right, the efficiency improvement used to be ~60% per two years now it's 7% per two years.
Is 3080 vs. 2080 Ti the correct comparison?
Given the 3090 is not too much faster than 3080, it seems there may not be room there. But then again, the 1080 Ti was as fast as the Titan X. So…yea.
I think 3080 vs 2080 Ti is the only possible comparison, but websites should make it very clear that it's an unfair comparison.
Probably the only comparison that actually makes sense is the (future) 3070 vs 2080 Ti. I'm not suprised that Nvidia pushed the release (it was supposed to be released earlier).