This is a great post.
One of the main tools that they could easily use to make the replayability of franchise mode even higher, is the 360/PS3 achievements. Here are some quick ideas:
Worst to first achievement - Win Super Bowl with Lions
Playoff Berth Achievement
Hire Best OC/DC
Balance the Books - Turn a profit for the team
Earn Home Field Advantage
Football Factory - Lose a restricted free agent with a top tender offer
Rudy - Have one of your practice squad players grow to a Pro Bowler
We Shall Overcome - Make the playoffs despite losing your best (at least 90+) player for the year during the preseason
etc.