McVay doesn't usually let these hires make off with chunks of staff. So I'm guessing KOC will be on his own.
He also doesn't usually hire from within either though so this will be interesting. He talks up Brown constantly, well here's your chance to show your love of the guy.
My guess is that McVay doesn't really want to teach a guy about, say, pass game coordination. So a jump for Brown who only has been exposed to the run side seems unlikely to me. Coach will have options to bring in who will be ready to go wrt the pass game. This isn't really a "learn on the job" staff even though he did that with Raheem. But Raheem is an old friend who he knew personally would be able to handle the change. So he's an outlier IMO.
I'm thinking someone comes in for OC from outside. He might make a run at a guy like Matt Campbell who can punch his ticket after one year in this offense. Dan Mullen would be another option there. But I'm guessing it will be someone like DeFilippo, a guy who has shown some stuff in the pass game already that McVay respects. Or an established offensive mind he knows well like Olson.