If Treveyon gets dinged while Miyan is banged up, then they have a real problem on their hands. That's an actual problem. Then you have to think about stunting Chip's ascent as a LB.
Losing efficiency for the garbage time carries where they aren't trying to get first downs is not a meaningful loss.
100% of the carries by RB4 + RB5 in 2021 were when the back of the bench was cleared.
The massive loss is Pryor not getting 50-70 touches as the RB3, and sprinkling 30 of those into real games. It's a huge loss for Pryor and the future development after Miyan goes pro.
As for replacing the carries when they aren't trying to score (and these aren't insults to these guys, merely speaking to who they can use)
They could get it to Cayden Saunders, or one of the frosh walkons.
They could give it to Mitch Rossi, or the next Mitch.
They could get Kaleb Brown involved in creative ways to get him interesting.