If you want to get seen and travel at the big events you have to play with Athlete's First. I highly doubt Carl Henry will be coaching the 17's now that Xavier will likely be going pro. Their 15's were coached by a different guy and I wouldn't be surprised to see him move up.
The summer scene has changed so much to where there are definite power structures and the have's and the have nots. It's much more difficult to start a team from scratch. Oklahoma doesn't have the talent year in and year out to have multiple teams in multiple tournaments. Having one really good teams allows the top players to really get a chance to be seen and to play against the best talent in the country.
That doesn't always serve the interest of the in state schools but I'm not sure that's what really matters.