Currently, the CFP distribution the net profits thusly:
P5 - 71.5%
G5 - 27.5%
ND - 1%
All others -0.5% divided equally
If a sixth G5 conference is created, the P5 are not going to give up any of their share.
The G5 revenue would be split 6 ways instead of 5.
For 2017-18, the G5 minimum guarantee is $81.32M. Split five ways, that amounts to $16.26M for each conference. Add another conference it it drops to $13.55M per conference.
That means that each G5 school would receive less. No member of a current G5 will join a new conference to receive a smaller slice of the pie.