I know you want to believe this. That doesn't make it all true. Let's stipulate things we can agree on, from above:
The NFL is a better on-field product than college - mmm, sure. It's pro, it's the top 2% of college players doing it as their job. It's also antiseptic and vanilla. I'd argue if we expand the product definition to include tradition, emotional connection to your university, the pageantry of the full experience, etc that college is better but whatever, it's not germane to this discussion.
That CFB fan interest will wane if their team is relegated out of a Power conference - again, maybe? We can cite counter-examples too, like TCU and UCF that have grown fan interest, or even SMU whose interest looks like a reverse bell curve with a big valley after SWC exit and death penalty and they've been building ever since into a pretty solid program with support. Their fans didn't suddenly disappear, in fact they grew.
CFP access - I agree that there should be CFP access for non-P2 programs. I don't think anyone is suggesting a B1G/SEC-only playoff. Now how do you balance the access is the question. AQs for non P2 programs seems silly if the Big12 champion has 2 losses vs. a 2-loss 3rd place SEC or B1G team who is stronger, played a much harder schedule and is ranked higher. But I could see reserving a semi-AQ if the Big12, PAC-whatever or ACC champ is top-15 or top-20 or passes some additional bar. In a 12 team playoff, 2-4 of those AQs seems ok and the rest based in ranking.
Now the stuff we might not agree on:
There are only about 5-6 programs in any given year that have the ability to actually win the playoff. They aren't BYU, Baylor, Cincinnati, Ok State or even mid-tier B1G or SEC programs. It's currently Alabama, OSU, Clemson, Georgia and maybe 1-2 others. In the 4-team CFP a smaller program might have the "puncher's chance" but it's like 5%. Cincinnati was the best example of the past 15 years, and they wilted. So no, those programs currently don't have a chance to win the championship, nor should that be their measurement of success. Competing for a conference title, beating their rival, and upsetting a blue blood (and before you say it, YES I'm aware of the irony of this statement considering the relative success of teams like ISU, Baylor, and OkState vs. Texas in the past decade). It's the illusion of access to the playoff and the dream we're talking about preserving, not the reality.
This gets even harder in the expanded CFP because now instead of having to beat 2 great teams to win, you a have to beat 4 of them. Teams outside the top tier of the new B1G and SEC aren't built for that. Good coaching can't overcome that. You need to stack top 5 recruiting classes, probably top 3 year over year over year AND have good coaching AND have good development AND the right facilities AND proper NIL support AND demonstrated success of putting athletes in the NFL. Only a handful of teams have all of that. In the coming years, the only ones who will have all of that are the top of the B1G and SEC which is basically true today with the possible exception of Clemson.
IF what you're claiming about smaller fanbases losing interest due to lack of access to a "clear path to a national championship" (direct quote from above) were true...we'd already be seeing it for the past decades. Because those teams don't have a clear path to a national championship as things stand today.
You might say viewership is down, but it's down overall for everything. Live sports and CFP pull big shares relative to everything else. Especially the marquee matchups between blue bloods. Those 4M+ viewership games are what is driving the realignment, going to 9 conference games in the SEC, etc - creating more of that inventory.
The butthurt here seems driven more by programs seeing their market value highlighted and codification of the status quo vs. something new. There's still the Vanderbilt and Indiana issue but no system is perfect, we're not building it from a clean sheet. I feel for the ISUs of the world who will take a revenue haircut. But they probably shouldn't have had the higher revenues to begin with.