Just read this on Yahoo Sports:
The Falcons are interested in re-signing OLB Stephen Nicholas — they issued him a restricted free-agent tender — but it's likely that he will be an unrestricted free agent when a new collective bargaining agreement is in place and that tender will be nullified. We hear Nicholas, a four-year veteran, is looking for an opportunity to start and be paid a starter's salary in a long-term deal. He might have to compete against 2010 first-round pick Sean Weatherspoon for playing time if he were to return to Atlanta. It appears, though, Nicholas will get an opportunity to gauge his value on the open market.
Sounds like the article assumes that Peterson is a lock. That would leave a big gap in the LB corps.