I believe if there is a week 18 no one is getting a bye.
It's actually quite possible the Steeler's will lose their scheduled bye week, lose their anticipated extended break with this weeks game being moved and also lose a first round bye. Two of those 3 things have already happened, just waiting for the that last shoe to drop.
Mark my words we'll see a week 18 game before we see a forfeit because when people keep harping on the violating team forfeiting, such as Ravens in this case, they keep forgetting that a forfeit would lead to a loss of a game check for BOTH teams. That, more then week 18, is what the NFL and NFLPA will be working to avoid at all costs.