Yes, his "brand" is doing fine. He went to Ignite and was a the third overall pick. He'll eventually get the full rookie exemption and be very rich. Scoot is going to be the second overall pick and if Wemba wasn't in this draft he'd go #1 overall, and his "brand" will be fine.
There are plenty of highly rated recruits who went to Duke or Kansas who have a "brand" in the NBA, and there are plenty who don't because they weren't good
Unless you just want to be a college student, this "brand" notion should be much less important than developing as a player in preparation for the NBA, and for players who are talented enough and who have the emotional maturity, it probably makes more sense to go to the G-League where you can spend all of your time working on your game with better developmental coaching in NBA schemes against grown ass men
If Mitchell has the option to start at Ignite (it's unclear if they want him), that’s probably his best move. If he shows he can guard up and down the lineup in NBA coverages vs that competition, he’s potentially a lotto pick next year as a role player, vs if he looks marginally better in college over last season he’s probably a mid second rounder
Hope he returns obviously