It was ruled out, But you never know now with a different show runner things might change.
Also i wish they'd stuck to the idea of having a stand alone episode at the beginning of each season.
It was originally planned to have at start of season 2 that guy who'd shot himself in the tank that Rick climbed into in the first episode. He was going to have an episode about how he got there etc.
Shame it never happened.
On the subject of a new showrunner, I'm worried that if AMC order a 4th Season larger than 16 eps the plots may become a bit thin. Having smaller runs is part of the attractiveness to non comic book viewers like me, does anyone agree? It was bucking the awful US tendency for 22 - 26 ep seasons? Also I view each block almost as a seperate season, so in my eyes 9 - 16 will be for me S5. Does anybody else agree, or for that matter disagree?