We'll just have to wait and see. I see 8K more or less as a gimmick, I don't believe many games, if any, will even support it. Might be more for apps like Youtube etc.Look I more than anyone want to get the maximum specs on hardware. But I follow Murphy's Law when it comes to product announcements.
The way they are wording things right now leaves them a lot of wiggle room. Notice how neither console specifies a frame rate for 8K.
I'm sure they will have "HDMI 2.1". The problem is that can be anything from 24 - 48 Gbps.