Josh Johnson is an interesting player on the Bucs' roster. He seems to be a solid backup quarterback, who showed that he could move the offense at times throughout last season. His poor performances in 2009 will haunt him, but he showed potential in those games, with his biggest problem being reacting to the pass rush. This year he seems to have improved his feel for the pass rush, and didn't seem to panic with players in his face. Instead, when asked to close out the game against the Pittsburgh Steelers, he took the Buccaneers downfield for the only touchdown of the game, albeit against a soft zone defense. He's also seen action as a QB in special packages, and was productive in those.
Clearly, this means Josh Johnson has some value for the Bucs. Unfortunately, he will also be in the last year of his contract in the upcoming season. He's expressed the wish to get a chance to be a starting QB in the NFL, a chance he will not get in Tampa Bay. This means he's unlikely to re-sign with the Bucs after his contract expires. Because of that, the Bucs could look to offload him while they can still get something for him instead of keeping him in 2011 as a backup.
Unfortunately, the Bucs don't have a good alternative as a backup QB. Rudy Carpenter has been with them for two years and should know the system, but he has a weak arm and seems destined to be a permanent third-string QB. And that's it, there's no one else. They could always get a QB in free agency, but without an offseason to learn the system and the verbiage it's doubtful he'd do much. In addition to all this, you need a trade partner to make a deal, and most QB-needy teams drafted a young quarterback high in the draft. Besides that, a team would have to give up relatively high draft picks, as compensatory picks would come the Bucs way if they let Johnson walk in free agency after 2011.
Looking at all these arguments, it seems clear to me that Josh Johnson will remain a Buccaneer in 2011 and serve as a backup. While there's always a chance he re-signs with the Bucs, it seems most likely that he will test the market after the season to see if he can fight for a starting job somewhere. He has the work ethic and the phsyical talent to be a starting QB in the NFL. If he can show that he's got a feel for the game, he may earn the job as well, somewhere. Just not with the Bucs.