Millen, a great sideline reporter but far from stellar team exec, led the Lions to a 31-84 record over his tenure, the worst record in the NFL over that time. Now Lions fans might rejoice at this, however they can't expect things to turn around immediately as a result.
Certain winless teams try to add a spark by switching quarterbacks (Vikings, Rams), and that can usually do the trick. Reason being is because the guys in the locker room view it as a spark, a quick fix switch that they can see. It's a tangible change from a player's point of view. Sometimes switching coaches can have a similar effect. Changing front office execs don't work that way.
Nothing will really change in the locker room, and don't de surprised it the already downtrodden Lions see this as the ultimate waiving of the white flag for the 2008 season. A new GM will come in and rebuild by putting his stamp on this team. A new exec brings in his own coaches and players, tossing virtually everyone's role with the Lions up in the air.
So while perhaps even the most optimistic Lions fan (if there is such a thing) might see this as a reason the 0-3 NFC North cellar-dwellers can turn 2008 around, don't bank on it. The Lions will limp along to the end of the season, at which time a new football guy will discharge large quantities of TNT into this franchise.
It will take a great deal of time to undo all that Millen has created. But, hey, the Lions are used to hearing how they aren't trying to win now (think Texas Rangers of the NFL). So when the new GM comes in talking about rebuilding, Lions fans won't expect things to get better ASAP.
At least it can't get much worse.