...and if the SEC and B1G expand beyond 20 teams, they are going to have their own growing pains and become too unruly w/ too many egos.
20 teams in a conference is no longer a conference and becomes more of its own league as it is. Once relevant teams will get lost, not like it, and look for other options (Oklahoma, USC, Texas A&M and others come to mind immediately) and may create their own offshoot conferences.
The problem with the SEC and B1G as it stands is that they have (especially the B1G) a relatively low bottom end... a true P2 would need to purge the Vanderbilts, Minnesotas, Miss St, etc and add the very best schools (which are constantly in flux as it is) to be a true P2...
...I just don't think it will ever happen. And Hot Take #2... if B12 adds FSU and Clemson, I think it could compete with the B1G and potentially even unseat it as #2 over time