Let's just play this out. And I'll agree with you [for the purposes of this post] that McCullough leaves this offseason. If that's the case, then the likely starting lineup becomes:
PG--Joseph
SG--Cooney
SF--Richardson
PF--Roberson
C---Bryant
Gbinije or BJ could start at 3 instead of Richardson--just speculating there. But adding in the newcomers, that leaves the following as bench players:
Gbinije
BJ
Howard
Diagne
Lydon
Obokoh
Patterson
Here's how I see the bench breaking down:
PG--Howard will either backup Joseph, or won't play much, with the more experieinced combination of Gbinije / Cooney / Patterson backing him up in some capacity.
SG--Gbinije could play here, so could Richardson. Patterson could as well, although if the newbies play well he could also be edged out.
SF--unlike this year, we'll return lots of experience at this position. If BJ finds his scoring touch, he could start or be the sixth man super scoring sub.
PF--not much depth here, and Roberson is a bit undersized. Diange will probably play a bit here. I don't see Lydon playing much next year.
C--Diange could back up here, as well. I expect Obokoh to play a lot more than this year.
So reviewing it all, I think that Lydon is the odd man out for next season--but will be the guy who emerges as a sophomore and provides us with some bench scoring.
This year, the 3 position to date has been a position of weakness, but it looks like a strength next season.
I'm not going to count on Coleman; if he returns and is physically capable, that changes the equation with the bigs a bit.
Of the incumbents, Patterson is the only one [my opinion only] who is in danger of having a more diminished role. If he doesn't find a way to work himself back into the rotation this year, he might be finished for his career in Orange, and I'd expect him to transfer.