They will probably give the back-up slot to Svedberg. It's time to learn whether he can play in the NHL. He was the best goalie in the AHL in 2012-2013 for the regular season, blew up in the second round of the playoffs, and really didn't play well this year after he was called up for one game, and sent back down. Moving him up will also give Malcom Subban a chance to show what he can do as the #1 goalie for the P-Bruins.
Johnson made $600K last season, and the Isles gave him more than a million. He wasn't getting that from the Bs.
They may move Loui Erikkson up to RW on the first line, and even though there aren't any quality FAs left, trades may still happen. They have a few players in Providence who they can plug onto the third or fourth line--Spooner, Fraser, and Florek. They're all left shots, though, but many players do OK on the off wing. Kelly should be ready to go by the pre-season, too. The third line really caught fire when they moved Kelly to LW and put Soderberg at his natural center slot.
The concern is that Iggy and Thornton were grinders who'd work the corners, and Loui is anything but.
Spooner is also on the small side, and he's never played wing, but both Florek and Fraser have some size to them.