Ian Rapoport of NFL Network divulged a few more details on Doug Martin's injury and his possible return this season. According to Rapoport the Buccaneers are targeting November 11 as his date of return, which would mean he would miss just two games: tonight's against the Carolina Panthers, and next week's against the Seattle Seahawks.
The Bucs will use the intervening time to strengthen Doug Martin's shoulder. If he reacts positively, he could return this season. The Bucs will have to be cautious not to rush Martin back and to avoid any further damage, especially so given the fact that they have effectively no hope of making it to the playoffs this year.
With Doug Martin out, rookie Mike James is expected to get the bulk of the carries while Martin recuperates. The Bucs have not been fond of running back rotations, so we should expect the other backs to be involved sparingly.