The idea that the Packers could use their franchise tag on quarterback Matt Flynn and then trade him has been floated from time to time, but the financial realities of doing so will be difficult.
Tom Silverstein of the Milwaukee Journal Sentinel crunched the numbers using the rumored $120 million salary cap for next season and found that the Packers are currently around $7 million under the cap. Franchising Flynn would cost in the neighborhood of $14 million, requiring them to release players to get under the cap. It would also limit their ability to sign tight end Jermichael Finley to a long-term deal before other teams had a chance to sign him as a free agent.
Per Silverstein, it is more likely that they franchise Finley and then get to work on signing center Scott Wells and/or cornerback Jarrett Bush. There would still be cap pruning required to bring back all three players, with wide receiver Donald Driver and tackle Chad Clifton at the top of the list of those likely to get the axe.
It is possible that the team could make those moves and a few others to retain their right to trade Flynn, but it seems like a less prudent decision if their ultimate desire is to keep key players from the core of a 15-1 team together for another run at a championship.