Exactly this, since the "have nots" actually outnumber the "haves" in each conference and they would NEVER support expulsion of a member.
The reason the "super league" stuff gets bandied about is it wouldn't involve "expelling" anyone -- it would be like ~16 schools all announcing at once that they are decoupling football (i.e. "leaving") from their current conference and establishing a new scheduling + postseason model independent of everything else. You wouldn't kick anyone out, you'd just be leaving them where they're at.
Most teams have little to no incentive right now to do this. Some -- like FSU, Clemson, etc. -- have TONS of incentive... but it's an impossibility for them because of GoR.
I don't see that happening because 1) as you said, the have-nots outnumber the haves; 2) the premier teams need Ws, and someone has to lose so it makes sense to keep the have-nots involved; 3) their TV footprint is still (?) the driving force, let's remember RUTGERS was pursued by the Big Ten less than ten years ago.
I see I still see four conferences reigning over football. A 20-team Big Ten, 20-team SEC, and either one 20-team conference or two 16-team conferences between the Big 12 and ACC.
With the pod format, really there is little difference between 14 and 20 teams IMO. The conferences should have been hard capped at 12.
My 20-team Big Ten works because 1) you preserve the pre-1994 Big Ten in two pods, rivalries generally stay in tact, 2) ND gets its California schools and then a usual Big Ten mix (Nebraska used to heavily recruit in California and it's probably the best deal they'd get), and 3) the eastern pod is really akin to something that could have formed if JoePa got his way.
I think Stanford only gets into the Big Ten as a package with Notre Dame, just as I see Duke getting in only as a package with UNC. A lot of people say the Big Ten will go for Virginia or Georgia Tech. IMO it makes more sense for cohesion to being UNC/Duke as a package. The Duke/UNC/Maryland/Penn State/Rutgers pod really actually works pretty well IMO.