Zero chance it happens across the board as I cannot see the Vandy's of the world opening themselves up to losing a bunch of SEC money just to help a G5 school get moved up to P5. The PAC-2 and G5 proposal may work because it is really only 2 P5 schools who likely would think of the themselves as able to stay out of the bottom 2 and therefore never be relegated. Therefore, it ends up being an chance for G5 schools to move up or down only.
The BIG10 or SEC would never participate in this. Nor would the ACC if it survives (unlikely). They would be locked in to their schools. This idea is trying to collect the remaining teams, out of the current 130, that would otherwise be left out in a creative way.
If the BIG10 and SEC expand to, let's say, 24 teams each and the BIG12 raids the ACC when it collapses to expand to a similar number...That's roughly 70 teams. Well, in the example from the tweet, the "PAC10" would collect 30 of the remaining teams and another conference would be created to collect the rest.
12 Team Playoff
SEC - 24 teams - 3 guaranteed playoff tie ins
BIG10 - 24 teams - 3 guaranteed playoff tie ins
BIG12 - 22 teams - 1 guaranteed playoff tie ins
PAC10 - 30 tiered teams - Top tier guaranteed 1 playoff tie in
"Last conference" - 30 tiered teams - Top tier guaranteed 1 playoff tie in
3 at large playoff tie ins
That solves a lot of the problems with super conferences.
I also think it would help if there were guaranteed matchups in the regular season amongst the SEC/BIG10/BIG12 and the two tiered conferences. I don't think you can disconnect them until the playoffs.