Agree it does seem to be the defenders who have their heads on the block, and if Brady was considered replacement for Miquel, that would still leave us needing to sign two centre backs and a right back to have a standard defensive unit.
I suspect some of the names mentioned will go, but equally wouldnt be surprised by the departure of someone deemed important who is perhaps more easily replaced.
Two centre-backs and a right-back?
Unless I've misunderstood your point, we've got Bassong and Martin, with Turner and R Bennett (and Miquel) as back up in the CB department. I know a lot on here aren't a fan of Rusty at CB, but his partnership with Bassong, in terms of clean sheets and goals conceded, was the best in the Championship I believe? So only if one of R Bennett and Turner leave do we need another CB. Investing in another one, say a very expensive but you g and talented, would be a luxury IMO.
At right back it's a little more complicated, with Rusty obviously doubling as back-up to Whits, and then E Bennett having played a few at right back. If E Bennett goes, we need a back-up right winger who can double as a fullback, but otherwise I'm not convinced we're short in that department at all (unless we want to invest in the luxury of a youngster).
I've said it before on here (as have others) I honestly see no reason why we shouldn't have the same starting line-up in the first game of next season as the last game of last... Any big spending should be replacing players on the bench with young'uns with potential. Dorrans and Mulumbu (if it comes off) mean we have experienced back-up in every department.