This doesn't mean anything, actually... it's just what they say when you ask about whether they're going to carry a specific designer or label that they've had before in the future.
As for P&B going-out-of-business sale, it's more likely that inventory is going to be moved during normal Gilt flash sales or moved into a permanent sub-store, like on Gilt Home and Taste. Though it's conceivable that they might have an all-P&B sale, I strongly doubt it.
Also for those holding on to store credit: some types of credit expire (not return credit, though). You should check that.