I think it was concussion issues with Shank. I don't think he could ever clear the protocol. Coach actually expressed some doubt about his coming back several games before the season's end...What will the offense line look like should be based on what the offense as a whole looks like. I know coaches want balance, but I'd like to see a greater effort put into having a core identity. I felt all year we were at least partly schizo when it came to our offensive identity.
I'll mention here that I think losing Shank hurt us maybe as much as losing Eddie and SDH. I say that because while he was a bit sluggish in pass pro, he was a very powerful run blocker whose presence was missed when we needed to become the running team that we clearly were meant to be. I don't know whatever happened to him but I hope he's okay.
If all goes well we have the potential for an all time great running game next year. There's no reason with our deep and mature group of potential o linemen and likewise the deep and mature group of running backs (plus N Harris) we won't be extremely effective.
Here's to hoping that the off-season is good to Jalen.