OK, having looked at the table, I'd be fine with defining GHC2020 (or is 2021?) as >= 8.
Also, I don't think getting additional input from the community would add any clarity to the process, at least not in ways significantly different from what we've already discussed.
Just for fun, my two biggest "disappointments" are:
* PolyKinds on by default, because I think that TypeInType is a mistake, but I am ok with it as in practice it rarely matters
* RecordWildCards not on by default, because it is a completely opt in feature, which is extremely convenient on occasion, and I find the arguments against it to be roughly equivalent to "I can think of ways to abuse this feature, so you shouldn't use it".
What are yours?
-Iavor