100% it would be a mess. Right now it's being done by a thousand papercuts. Eventually they will have have no bark to go along with their increasing lack of bite and it will be a bigger mess.
If I told you three years ago that a former NBA player was now eligible to play, you'd never have believed me. What's the equivalent to this three years from now? NCAA variant? Private equity? Super conferences?
Also, I know the NCAA tournament is probably the best sporting spectacle outside of the world cup and super bowl, but how hard is it for another company to get investors and host their own tournament? If you can disrupt the tournament, that will be the final blow for the NCAA.