I assume they will extend Lester, though, at probably 5/90-100. They'll lose 15.5 of Lackey, and Peavy is actually 16.5, not 14. Plus Dempster's 13, so they'll lose (including Lester's $12) $57mm off the books, add $18-20mm, so they'll have ~37-39mm to play with and really have no position players to replace. I would assume the rotation would be something like Lester Buchholz Doubront, and then two of Barnes, Ranaudo, Workman, Owens, Webster. But again, you go get Tanaka, and you can probably dish a few of those prospects for a big bat in LF.
This obviously isn't even counting the loss of Pierzynski, Ross, & Gomes (~18mm), two of whom can be replaced internally with Brentz and Vazquez, and then sign a backup C.
The Sox will have a ton of payroll flexibility going into the 2015 season. And there are some very intriguing names hitting free agency. Clayton Kershaw, Justin Masterson, James Shields, potentially Tanaka (give me Kershaw, plz)