IMO, I think the IOL will be okay. Mason and Jackson are rookies who both have potential. If the next OL coach can better develop them, they'll be good. Maybe they bring back Wendell and see if he can help.
The tackle situation is the issue - I think I've said it already but Vollmer and Cannon are probably both overpaid. Think Vollmer needs to restructure, as his salary is too high for his age for his position. If not I wouldn't be surprised if he was gone. Don't know what they'll do with Cannon... He's decent as a "break glass in case of emergency" tackle, but if he's starting then you've got problems. Fleming sucks. I liked what I saw in the very few snaps Waddle took and would like to bring him back. He's not signed for next year, right?
Wouldn't be surprised if they moved on from Vollmer and Cannon and tried Waddle at RT with Fleming as depth (cheap contract - if your depth sucks, it may as well suck cheap) and bring in some OTs late in the draft or UDFAs hoping to find a diamond in the rough.
They could always try to sign Okung, too, but that doesn't seem likely.