The most important issue is not how many teams make a national playoff. The bigger issue is what happens if The Alliance (Big Ten, ACC and Pac 12) finally decides to go one way and the SEC and Big 12 go another way if they can't agree on a new structure for the college playoff. Who would you be pulling for?
I would suggest it's more of SEC v. The Alliance. For football, what's left of the B12 is really irrelevant. They might come along with the SEC, but they will be following, not leading, IMO.
From what I have read, the way the NCAA is currently configured, 3 of the P5 conferences have to agree to a rule change - in this case, how to configure the CFP. This comes from a 2014 change in Division I where the whole P5 G5 nomenclature came from. The P5 were given autonomy to make their own rules after they complained that the G5 teams/conferences had too much influence on things that didn't really relate to them, or affect them. Here is how I think this has to happen:
"There will be two ways to pass new rules: Get 60 percent of all the votes from 65 school representatives and 15 athletes plus a simple majority from three of the Power 5 conferences; or get 51 percent of the votes and a simple majority from four of the five Power 5 conferences."
This basically means that the Alliance has the ability to veto any and all legislation about the CFP if they want to. So, on one hand you have this odd alliance where the B1G just doesn't fit. Then you have the SEC which is the big kid on the block. I can't see any scenario where the SEC will compromise on anything that is important.
Per OP's reference to The Athletic, they have an article that talks about the SEC either (1) doing it's own 8 team playoff and then having an SEC champ on Jan 1, and telling the Alliance that we will be in Indy (or wherever) on January 10, send your champ to play us. or (2) having tournament with the SEC, B1G, and the G5 and maybe ND.