As much as I hope you're right in the bolded part, I also hope you're wrong. Isaac Haas and Vince Edwards both will test the water in the NBA, and both, along with Biggie, will more than likely withdraw their names.... BUT, if these guys go nuts, dominate the B10 (which is very possible), then all 3 could be gone, and now we have to rely on Wheeler and Kristap Porzingis lookalike, Haarms, and lord do I wish he is half as talented as him.
That said, I think it'll be just as long of a shot for OG and Blackmon to leave for the NBA than Edwards, Swanigan, and Haas. Bryant is for sure gone, as he'll likely be a lottery pick, but Blackmon coming off a torn ACL, will need to be a freak of nature just to give teams the confidence to pick him in the first round, being injury riddled, and OG gets lost in the flow too often, and if Blackmon shoots as many times as he did his freshmen year, then he may get lost even more, thus not being able to showcase his full ability. Still, teams will reach for a 6'8 freakishly athletic wing like OG.