The only "big" name so far has been NPH, we are talking the double whammy of Doogie Howser and Barney from HIMYM.
All the other Hedwigs (Rannels, Michael Hall, Darren Criss, JCM, and the upcoming Taye Diggs) are all known in some circles but nobody is some sure fire draw with proven Box office track record.
The "content" matter isn't keeping people away either , not on BW that keeps Kinky Boots and BOM going.
Quite frankly, the show isn't built for longevity, it's getting "old" like so many other shows past the year mark.
"when I’m on stage I see the abyss and have to overcome it by telling myself it’s only a play." - Helen Mirren