It tried to explain things away. The issue is that people tend to hang onto their AVR for 10-20 years. They'll replace their console and TVs before their AVR.Watch this Audioholics Denon Sound United presser. It will explain away your concerns on the 40Gbps and single 2.1
I'm quite sure we'll have 12-bit panels within the next 10 years and for sure in 20. I also like to know how he knows the Xbox One X and PS5 are going to be 40Gbps maximum. And in 10 years you don't think the Xbox Two X and PS6 will not be 48Gbps? PC video cards will hit 48Gbps either at launch or not too long after.
As for the single 8K input, use eARC? Sure. But then people with TVs that have three extra 40/48Gbps ports, or one extra 40/48Gbps port and a single console, don't really need an AVR with HDMI 2.1 features at all (except for eARC). With an eARC audio extractor they don't even need eARC on the AVR.
Ironically it's the non HDMI 2.1 features that have me interested.