In my opinion, the more of these that sell out the closer we are to the removal of EMH (or more reductions in it). Once Epcot has more/better attractions, I would gather they will start doing these there as well.
As it stands now, for my upcoming trip next week (24th-28th), there are more options for EMM or DAH events than there are EMHs.
Or .. the closer we are just to these morphing into several months of "Spring Fling" parties -- where they have several times a week like they do with the Halloween and Christmas parties.
I just wonder how many tickets is a "sell out" for these things? Always curious how limited they are (and I know they would never tell us0.