I think short of taking transfers, the coaches are doing about all they can do or are going to do. I don't see them sacrificing the d-linemen, except (possibly) Hounshell, and I doubt they'd want to move even him.
Watt (one hopes)
Martin (one hopes)
Lombard
makes three starters back. Golic, tho improved, should be able to be replaced competently (at least) from within. Lombard may even slide over to take his spot and someone else take Lombard's place at tackle. Center is the biggest concern, but Hegarty was being groomed for it and was a top recruit - until we hear any more or any more definitive statements on his long-term situation, we can't really have a good discussion about this. Assuming the two guys return for fifth years, I think we'll be ok next year, although obviously if Hegarty isn't around it would be a challenge.
This will sound wrong, but o-line depth is a luxury. If you have 8 guys on o-line you feel comfortable putting out there, you'll be fine most years.