Episode 3.13 - Arrow on the Doorpost In an attempt to put an end to the killing, Rick and the Governor decide to meet in hopes of finding a peaceful way to resolve their dispute; but having trust develop between the two may be too high of an expectation
Episode 3.14 - Prey The Governor chases a fleeing dissenter; while the Governor is gone, a traitor tries to sabotage his plans.
Episode 3.15 - This Sorrowful Life Rick and the others learn that if they want a truce with the Governor, they must make a sacrifice.
Episode 3.16 - Welcome to the Tombs Rick and the others consider the defense of the prison as the Governor's impending attack looms.
Okay so, I think that this is how things will go:
312: Road trip/filler episode about finding Morgan.
313: Since Andrea cannot bring herself to kill the Governor, she sets up a meeting for the two to discuss a peace treaty.
314: Tyreese leaves Woodbury for some reason and Andrea sabotages the place while the Governor is gone. The Governor takes Andrea as a captive like he did Michonne in the comics.
315: The Governor says that for the truce to work, they must hand Merle over. The Governor plans on executin him but Merle escapes and won't show up again until next season.
316: The Governor decides to attack the prison because Merle escaped and now the truce is broken. Rick takes Karen captive somehow and plans on trading her with Andrea and starting their truce. The Governor refuses. Rick gives the "We are the Walking Dead" speech at the end while Andrea mutilates the Governor like Michonne did in the comics.
With the Governor being injured, he cannot attack. Therefor, Andrea returns to the prison and they all live happily ever after there for the start of season 4...until Merle shows up to exact revenge and The Governor heals.
However, this would allow the prison arc to extend through at least half of season 4. Maybe all of it?