Along the offensive line, this is my best guess:
Center: Johanning is a beast and looks to move from OG to C this fall. The only other players listed on the roster at C are Ryan Lamb and Luke Westerman. Last season, Lamb was listed as backup C.
It is probably worth at least mentioning that last season Wyatt Huges started one game at Center in Jumper's absence. Hard, though, not to expect the starting guy in the middle will be Johanning.
OG: Wyatt Hughes, I believe, has logged 17 starts and 26 games. He was RG last year and, I expect, would seem likely to man that role again this year.
The other OG (presumably, to take Johanning's spot) seems up in the air. The two OG backups last year were EJ Wilson, who logged limited time, and Blake Hundley, who appears to have moved to OT.
I would expect this spot would likely go to Gerrik Vollmer or newly-acquired Fred Norman.
OT: Pearson Toomey seems like a mortal lock to start at one of the tackle spots. Eli Brasher was listed at #2 on the depth chart, but played sparingly. Luke Petit is another guy that you may start seeing work in there as well.
I expect the other OT spot will be one of the transfers. Either Norman or one of the other yet-to-be-named transfer players.
At bottom, the offensive line returns everyone on the 2 deep but Tomlin. There's a ton of experience up front and a few guys that have been waiting in the wings ready to contribute.
We didn't have a ton of depth last season, but, fortunately, didn't really need to call on it. A lot of the backups were younger players and guys that could swing at different positions if needed. I think this year we'll still have the veteran/talented starting front, but the backups will have more depth and, I would expect, the ability to rotate into and out of the game more frequently.