Depends on what mock draft you look at but as of present day a good chunk of North American players projected to go in the 1st round are either playing NCAA or already committed to an NCAA school. (and that doesn't include Mathis Preston, Carels, Ethen Belchetz, Ryan Lin, Daxon Rudolph etc)
I think this summer will finally be the writing on the wall moment. If around 80 to 90% of North American players picked in the 1st round all have NCAA ties they'll come to the realization of the new reality. (especially considering there might be 0 USNTDP players picked in the 1st round)