In general I think there is a reasonable case for special treatment for exceptions to H98 that have been accepted for haskell-prime.
I'm not sure I agree with this. I'm not involved in the H' process, but it was my impression that the general state of affairs was a move towards a modularization of the standard, so instead of a single monolithic Haskell' language we would have a series of blessed addendums like we already have with e.g. the hierarchical module namespace or FFI. If that's the case then having each of those addendums enumerated as extensions makes perfect sense to me, at least until a H' standard (in whatever form) is actually released. That said, this really have little bearing on the current discussion, since as you say this particular case won't make it to H' anyway. I don't really see any good arguments why MonoPatBinds shouldn't be the listed extension. Cheers, /Niklas