A few thoughts (more about his draft decision process, not his talent):
1. The conventional wisdom used to be to leave if you're a first rounder, largely due to the guaranteed contract and the likelihood you were booking a plane ticket to Europe if you weren't a first rounder. However, given the evolution (and lack of stigma) of the G-League, the availability of affiliate/2-way contracts, and the like, I suspect that it'll be more common for players to leave even if they don't think they'll go in the first. It's already starting to happen - looking at the second round of last year's draft there were a bunch of sophomores picked that I don't recall ever being mentioned as likely 1st rounders. Maybe “second round pick with a 2-way contract and a verbal promise to spend 45 days with the NBA team” is the new “first round guarantee.”
This will happen to us eventually, and I predict several posters here will have coronaries arguing about it in the thread.
2. The idea of “playing your way into the lottery” as an upperclassman is almost extinct.
In last year’s draft, zero upperclassmen were drafted in the lottery. The first senior wasn’t selected until pick 29. The first 11 picks were freshmen (plus Ntilikina, an 18-year-old foreign player). It’s been five years since there’s been more than one junior selected in the lottery, and while I wouldn’t put much stock in mock drafts at this point of the season, there seems to be only one that is being considered this year (Bridges from Villanova).
There’s always a contingent that says “bet on yourself and come back!” every time a player is considering going pro, but for most players that would seem to be a bad bet.