There will be a lot of pressure on Michigan to play next weekend because there is almost no way the B1G average games per team will stay below 6.0 (actually, it may have to stay below 5.5, which it has already passed). If undefeated Ohio State cannot play in the B1G championship game, does that automatically keep them out of the CFP?
There a several scenarios, but most likely is that the CFP will simply ignore the B1G rule and accept Ohio State at 5-0. Another is that the B1G revises their rule, thereby allowing the Buckeyes to play on Dec 19th. Another is that Ohio State is left out.
My guess is that the outcome of the ACC and SEC championship games could nudge the CFP committee one way of another. If Florida were to beat Bama, that would really make an SEC decision difficult. There is precedent for accepting Texas A&M, even though they were not the champion. Would Bama be left out? In the ACC, I think Clemson has to beat ND to be in the playoffs. There are five really good teams from the ACC/SEC and none would be a bad choice. If ND and Bama win on the 19th, it makes it easier for the committee to accept Ohio State at 5-0. That is the scenario that lets A&M be the fourth team.