> I think Haskell needs a way to graduate (or retire) language extensions, rather than having them accumulate unboundedly. It's harder to talk about Haskell when everyone is using a different flavor of it.

That is what the standardization process is for. I don't think that the parties that could write a new Haskell standard have the time, resources, or bandwidth to work on one. That's why for now we're stuck with 98, 2010 and a bunch of extensions.