I agree with all of the above. However, I'd be shocked if it happened. Expanding the NCAA tournament has only ever been about increasing the number of major-conference teams that make it:
1. For revenue generating and sharing purposes for conferences. P5 conferences have the power and influence to negotiate with the NCAA and make way more money off the tournament than smaller conferences: https://www.sbnation.com/college-basketball/2018/3/30/17131466/how-much-money-do-colleges-make-off-the-ncaa-tournament-every-year
2. For revenue generating purposes for the NCAA - larger and more well-known schools will draw more fans in seats, eyes on TVs, etc.
3. Because there is a belief that the sixth, seventh, or eighth team in a P5 conference deserves to be there more than a worse mid/low-major team because they are better, played a harder schedule, have a chance to go farther, etc.
Life most everything in life, it's all a game of incentive economics. The NCAA tournament is the revenue-creating engine of the NCAA. If anything, it will only continue to expand (like it continues to) in some format. We're now seeing the same with the CFP.