If I had to guess I would say something like late 1st round. He's not "NBA ready" per se, but honestly how many of the 1 and dones are polished athletes when they go pro? Jaren Jackson was maybe the 3rd best player on MSU last year and got picked #4. Mo Bamba was 6, Kevin Knox 9, Shai Gilgeous Alexander 11, you can go on, all had lots to improve... even the presumptive #1 next year (Zion) doesn't have a good perimeter shot right now.
I do agree that he needs to improve his 3 to have success in the NBA, I just don't think that'll stop a team from taking him sometime in the first round due to his athleticism and ability to score. Development doesn't stop when you get drafted. He could / should be a pretty good defender in the NBA too if he puts in the effort.