It's a sort of d*mned if you can and a d*mned if you can't situation.
These are not the kinds of players who are wildly overpaid as merely adequate performers who hold onto ether their starting positions or at least a roster spot because of dead cap with the handwriting clearly on the wall. (See Hawk and Jones, 2014).
It's a d*mned if you can situation because if the players' performance falls off you may get cap savings by cutting them but then you have to replace that player's past performance that earned that contract in the first place. Keeping the player with a contract negotiated down amounts to the same thing...the performance that earned the contract in the first place is not longer evident.
Unlike many rosters, there simply are no players hanging around on the Packer roster with merely adequate performance, a big 2016 cap hit and a big 2016 dead cap number, while having a big cap number in 2017 with a sharply dropping dead cap number who would be an obvious choice to cut to get a big chunk of cap space.
As for extensions, pushing cap out a couple of years, the candidates are not so obvious. Here are the top 2017 cap hits and the age at which the current contracts expire:
Rodgers: 2019, age 35
Matthews: 2018, age 32
Cobb: 2018, age 27
Shields: 2017, age 29
Nelson: 2018, age 32
Daniels: 2019, age 30
Bulaga: 2019, age 30
Burnett: 2018, age 29
Given the age of most of these players and the uncertainties relating to performance in the years past those contract expirations, with the exception of Rodgers I don't see anybody here who be worth the risk of an extension knowing what we know now.