I love all these elaborate plans and explanations of how the playoff should be run. But they're a total waste of time and effort. However much you may want to see it run the way you've outlined, the people who run the playoff don't.
The P5 will do everything it can to keep the present system without any changes for as long as it can. If there was to be a true, fair championship set up, it would be done by the NCAA, who would get all the money from selling the TV rights as they do from CBS and its partners for the bball championship. However the P5, and the G5 for that matter, are in no mood to surrender a dime to the NCAA following the Regents of Georgia and Regents of Oklahoma v. NCAA SCOTUS cases said they didn't have to give them the money for non-NCAA championship events. Right now, the P5 gets the money from the playoff and the G5 gets $0.00. They want to keep it that way. Any set-up that brings in a G5 conference reduces the money going to the P5 conferences; that's a non-starter. If there was a way for the P5 to take the money from bball away from the NCAA, they would do it in a nanosecond.
Many people thought there would never be a playoff, then came the BCS games and now the playoffs. Expansion of teh playoffs is not a stretch, especially when one considers the lower levels of CFB have a 16 team playoff!
The issue of the NCAA football championship going to the NCAA has been discussed ad nauseum in other threads, you are correct that the NCAA will not see a dime of the bowl revenue, especially when one considers how they get half the NCAA tourney money, have an over-bloated staff and still manage to screw up nearly everything they touch. That said, the P5 need the G5 for fodder. Teams are only allowed one DIAA game and the B1G has banned them in the future. Thus, to rack up the minimum 6 wins, there needs to be a pool of beatable teams outside the P5. Otherwise, the bowls drop in number and the eligible teams are reduced because of a separation from the G5. If the G5 does not receive enough of a payday and at least an appearance of opportunity, they cannot generate enough money to stay in the D1A grouping (P5 and G5). The P5 needing the G5 for fodder is one reason that P5 hasn't spun itself off from the NCAA, they need fodder in football and hoops to keep the big cash rolling in.
Leaving one of the P5 conferences out of the playoffs was barely acceptable.* Leaving two out, especially when there is reasonable debate regarding Alabama, is devastating to the process. They will figure a way to get at least the last P5 team in, whether 4 & 5 play first and the winner plays #1, or the expand to 6 or more teams. Will it happen overnight? Probably not. Regardless, the bowl system is their money generator with TV rights, they will find a way, and they will incorporate bowls if possible.
*It was acceptable when many thought the Big 12 or the ACC would collapse. Fox Sports' and ESPN's deals with the Big 12 and with the B1G have proved there is far more money available that previously thought. With more cash available, the conferences have no reason to devour the Big 12 (or ACC - which is not likely to happen, regardless).
