They're actually selling tickets through January 30th, but this as always been the plan. If it somehow turned into a big hit they would've found a way to extend, but the cast were all signed just through January.
Actually, according to every article i have read about it,the cast is leaving the 30th. it doesn't say the show is closing anywhere. That might mean they are bringing in a new cast.
When it opened, it was advertised as an open run. Weird.
It actually wasn't. It was always a limited run through the end of January with hopes of extending if it did well. They only advertised through January 23rd though as the cast signed until then and would be leaving afterwards no matter what (now they've extended a week, but they are still leaving at the end of the extension).
That playbill end date has been there since the listing was put up. I remember seeing it when it first showed up as playing at the Cort.