LCT is a not-for-profit organization, they can't give a show an open-ended run. You'd have to find the thread where Margo Channing explained it in detail. But I have a dream that some people with big hearts and even bigger wallets(HUGE wallets) would transfer it to a permanent theatre.
This week, I read that the Vivian Beaumont theatre doesn't have a show set to open in it for the upcoming season so maybe LCT will keep Piazza open until another show needs the theatre. I don't think a show gets much better than Piazza so why try, eh?
"I'm the STAR!"--Daniel Reichard during Glory Daze sound check