Which extensions should be part of the next GHC20xx?

The GHC20xx language editions seek to collect commonly-used and generally accepted extensions under a single flag. (Unlike Haskell2010, there’s no full standardization process, just the GHC user’s guide documentation.) Given that we now have GHC2021 and GHC2024, we should start to think about GHC2027! (There’s no “official” decision to make GHC2027 the next iteration, but it would seem natural.) Which extensions would you like to see included? To get things started, here’s my wishlist: CApiF...