It there is not enough elgible teams for bowls, then what happens.

[tdydynasty]

If it is an open slot, the other team wins by forfeit.

If it is 2 open slots, the game is not counted at all.

Just suppose if there are not enough 6 win teams then the NCAA should volunteer old time players to play the games.

[Solecismic]

They changed the eligibility rules to pretty much ensure this doesn't happen. Given the amount of money the sponsors guarantee, I can't see the NCAA turning down the opportunity, even while grumbling about dilution of interest.

At some point, the sponsors will reach a critical mass, and new games meeting the criteria will not manifest. It may take a few more years, as it's all about getting alumni and students willing to pay for vacation packages, and so there's a novelty effect for schools like Rutgers and Ohio University, which, in the past, would go 20 years between bowl appearances and now might go three.

The question is where the NCAA will place that minimum bowl offering, and that decision is made based on the effect dilution has on what would be more interesting games. In the meantime, it's fairly easy for them to continue to adjust the eligibility rules to guarantee every bowl gets filled (and if not, grant an exception, as they have in the past).