The overwhelming majority of the coverage has talked about how BYU is the obvious best choice. I know there's been a few nay sayers, and some politicking involved, but there is almost a consensus that BYU deserves to be in.
Imagine the public backlash from fans and the media if they added some combination of Cincy, Houston, UCONN, or Memphis and didn't include BYU. This wouldn't help their perception as being the most vulnerable P5 conference. The B12 knows this.
I know it's not a done deal, and nothing is out of the question when B12 officials are involved, but there's no question that the vast majority of people feel BYU would strengthen the conference. The B12 isn't stupid enough to overlook the way it would be perceived if they left BYU out.
Maybe.