Sister Act is almost approaching one year on Broadway which is not bad by most measures. It's one of only three new musicals from 2011 that's still playing and I suspect Priscilla's days are numbered too. I doubt it's come near recouping and it's probably purging money the past few weeks but to write off as a complete failure is unfair when it's compared to a lot of other shows.
I don't see how the show survives more than a month or two and I say that as a Sister Act fan. I can't think of any star that would come in at this point to bring up the grosses (not to mention that Patina's under contract for another two months).
Scratch and claw for every day you're worth!
Make them drag you screaming from life, keep dreaming
You'll live forever here on earth.