After essentially serving as the Detroit Lions' sixth starter on the offensive line last season, 2012 first-round pick Riley Reiff is expected to become a full-time starter in 2013. It's not clear right now where he will start, but he is expected to crack the offensive line's traditional starting lineup.
Another offensive lineman for the Lions who could potentially make the jump to starter is Jason Fox. He has gotten far less attention than Reiff because he was active for only one game last season, but the Lions consider both players to be ready to start. Lions general manager Martin Mayhew said this when asked about them last week at the NFL Combine:
"Both those guys we think are quality football players, are going to be good players for us for a long time. Jason Fox obviously had the injuries first couple seasons. He was able to stay healthy all last year, but we also stayed healthy at the tackle position. He didn’t play very much for us. We think he has starter type talent level. He has the size, he’s a strong enough guy, he’s a good technician, he’s a hard worker. We think he has the ability to start for us."
Lions head coach Jim Schwartz had similar thoughts about the two players, saying that they have "developed those guys" and are prepared to plug them into the starting lineup if they are called upon. Reiff is poised to take over for Jeff Backus should he retire, and Reiff could potentially replace Stephen Peterman at right guard or Gosder Cherilus at right tackle. Fox is also a candidate to step in for Cherilus at right tackle.
The fact that the Lions seem to think so highly of Fox suggests to me that they wouldn't be opposed to sliding Reiff inside if Backus returns and Cherilus departs. The left side of the line would remain unchanged in this scenario, and you could have Reiff at right guard and Fox at right tackle. Chances are this would be a one-year thing unless the Lions draft an offensive tackle fifth overall, but it would be one way to fill the vacant starting spots without having to address these needs through free agency or even the draft.