I agree with one part of your post - the Munster SH Championship is an institution and the GAA would tamper with it at their peril. They tried years ago with Galway "competing" in it and it was an abject failure - I can't remember Galway winning a single match or adding any spice to an already highly competitive series of games.
The Leinster SH Championship, given a bit of time and investment, has the makings of a good competition (maybe excepting Kildare and Wicklow currently) but parachuting Antrim, Galway or whoever into it, adds nothing, IMHO.
So what to do? Two provincial championships, a "displaced persons" championship and a separate All-Ireland series, is one possibility, but it would need a longer season to accommodate the extra matches, with qualifiers as per the Euro soccer.