Never going to happen, ever.
Last year when the PAC 12N and Teaxas failed to reach a common ground aka equal rev sharing, Oklahoma and OKS were still on the table, all that was needed was the final Ok from the Presidents. This was after the 75% rule change. As we know that didn't happen. If The likes of Oklahoma and Oklahoma state can't make it past the PAC 12 Presidents, BYU has no chance. They don't like, what they don't like.
Larry can be as innovative as he wants to be, at the end of the day, the presidents and chancellors call that shots and sign his paychecks. And the last thing he is going to do is anger the 12 guys who just made him the highest paid commish in the business.
The B1G, like the PAC 12, is very vocal against further expansion. They make up half of the "Big 4". That will be enough to curtail crazy expansion for some time. What ever play off scenario is adopted will likely reflect that.
Also, I don't understand why BYU woul want to be a part of a conference that doesn't want anything to do with them. Afer ESPN is done slapping the B12 on the hand for destabilizing their red headed step child, aka the ACC, with whom they just invested a ton of money, they'll probably drop the whole FSU Clemson thing and eventually pick up BYU and someone else to get to 12.