Well, it's Black Monday. Rex Ryan and his GM John Idzik were finally axed by the Jets. GM Phil Emery and Marc Trestman were fired by the Bears. And Mike Smith got fired from the Falcons.
Of course, Jim Harbaugh is going on to coach Michigan. I think that letting Harbaugh go will be a mistake for the Niners. Not everything Harbaugh did was on point (letting Alex Smith go wasn't the smartest decision, IMO), but he's light years better than anything else that could possibly be available to the Niners at this point. They might strike gold, so to speak, but I don't know if they'll do it so soon after Harbaugh.
I consider 3 division championships, 2 NFC championship games and 1 Super Bowl appearance in 4 years to be a success. I would not mess with success like that.