I think one solution that seems reasonable is for FCS to grow and include the FBS schools that aren't in a position to compete in the NIL era.
Let those 6 - 12 teams compete for the CFP, LLC championship. Schools like CU and VT can still have a meaningful and relevant football program that more resembles the college athletics we are accustomed to.
I've mentioned before that I think the only way college football survives is with a major restructuring.
The top 30-40 schools who want to be in the big money game (it will start with more but the realities will force some to filter out) will be in the top tier, collect the biggest part of the national TV revenues, and most will still struggle to break even because of the arms race with paying coaches, players, facilities, etc. This group probably goes with it's own governing body leaving the NCAA for football. CU won't be in it.
The next tier will be most of the schools who were formerly P5 programs plus a few top G5 programs. This level will build in some cost controls limiting NIL, and potentially limiting coaching budgets and maybe even reducing scholarship numbers. They will still get some national TV money along with local or regional money since there are a lot of networks out there with programing slots to fill and most of these schools have enough loyal or at least interested fans (plus the gamblers) to generate audiences.
Below that you get a level with most of the former G5 plus the top of the current FCS. More cost controls, get by mostly on ticket revenue and donations.
Lower FCS joins current D2.
Having the upper division handing out money allows the others to limit their cost and benefits since they aren't a monopoly.
Schools and fans will initially try to make the argument that they have "always competed at the top level as is fitting for an institution like we are." but realistically the fans of most of those schools know that they haven't been "competing" at the top level of years and short a sugar daddy billionaire donor or two never will again.
Some schools may see some decline in fan interest but in general the idea that their team is actually competitive and games are fun again will be more appealing that watching them get their teeth kicked in by higher budget programs every week.
Basketball could see a similar shakeout or we could just see it made irrelevant by most of the top talents going directly to NBA development squads or to international leagues at more money than the NIL would be anyways.