Unlike Spiderman, there isn't that minimum audience set. Just see how (barring Nolan trilogy) other Batman movies have yoyo'd at the BO. Success of one doesn't guarantee that of the next one. There's still time to reconsider.
From what I see today people are already prepping for having $30.3m free by Sat (most of the $ seems to be moving within WB/DC fare). Needless cull.