1) The schools in the Big 12 care about the sport more than schools in other leagues. That's not going to change quickly. They invest in the sport at a level other programs simply don't care to, and likely won't at the risk of their football programs. It's not an advantage that can't be replicated, but it's an advantage that likely won't be replicated.
2) The NCAA is not long for this world. There will be a day when the college basketball tournament is no longer controlled by the NCAA, and that day isn't far off.
The whole point is that long term there will be enough financial incentive for the most powerful football conferences to keep playing basketball against the best basketball conferences. The Big 12 can never financially match the SEC and Big 10, but by being the absolute best basketball conference they can bring enough value to avoid getting cut out of football, which is really all the fans and administrators want. Our doomsday scenario is being shut out of the highest level of college football and the best way to avoid that is by creating enough cumulative value that the Big 10 and SEC find value in keeping others at the table. They'll still get the most teams in football, make the most money, and win the most championships. The CFP, and all college football, will get better ratings by at least having the appearance that anyone can qualify if they take care of business. A formal separation, while still financially viable for the SEC and Big 10, would almost be guaranteed to draw fewer eyeballs than they currently do, but there are an awful lot of people who seem more motivated by the air of exclusivity than by what's actually going to make the most money in the long run, so it remains a risk.