Their defensive backfield depth is nothing without Sean Richardson. If he did leave, then there's no one behind their top five defensive backs currently on the roster that even played one snap on defense last season. The cost of an extra $1 million (Richardson's tender is already on their cap at $1.5 million) might be well worth it for a reliable defensive back.
Nick Perry and Datone Jones would have about the same cap charge as Richardson next season. While both are former 1st round picks and more a part of the regular defensive rotation than Richardson, both of them had play counts last season below at least three other players at their positions. In 2014, Richardson had about a third of the snaps that either Perry or Jones had, but it's not a stretch to imagine a larger role for Richardson in 2015 with Tramon Williams and Davon House now gone.
He'll cost more than they wanted him to, but I bet they keep him for next season. Otherwise they'll have to kick the tires on a current street free agent or two to find someone who can replace him.
Packers might let Sean Richardson leave - ESPN (blog) http://t.co/mJETnluqgR
— Green Bay Packers (@PackerNews) April 8, 2015