zach

The bigger question is not whether Zach comes back, but whether the show comes back? Prospect Park announced months ago that production on season 2 was supposed to start on October 21, but as now, there is no production date to begin filming AMC's second season. This is similar to what happened after PP filmed the first 40 episodes of OLTL and 43 episodes of AMC when they took a "hiatus" around July and said they would resume production in August, but then announced that the shows were ending their first seasons rather abruptly.

IF (and that's a big if) AMC resumes production, I would assume that Zach would not be replaced, but off the canvas. It could easily be explained that Zach reunited with Kendall and the boys.