While I think Zion will play in the NCAA tournament, not sure how anyone can declare that to be a fact. Yes, Zion can and will play basketball before the NBA draft, but literally the moment that Zion elects to play no more college basketball, Nike, among others, will offer Zion endorsement contracts that will set him up and everyone else in his family for life. So, he will play those pre-NBA draft workouts/games with 8 figures plus in the bank. While Zion likely would get those deals even if hurt himself again in the tournament, there is some risk if he suffered a catastrophic injury that the endorsement money would not be the same.
With that said, the kid seems committed to return, and it appears he will. Even so, wouldn't be shocked if ZW has played his last game as an amateur.
Barrett, Morant or someone else may turn out to be a better pro, but barring a revelation that his injury is a long term issue, Zion will be the first pick of the draft. The NBA is entertainment, and Zion is and will be the show for years.