Dave Erickson, executive producer of Fear The Walking Dead, has signed a multi-year overall deal with AMC, the network behind the hit The Walking Dead companion series. Under the pact, Erickson will remain an executive producer of the series, but leave his role as showrunner at the conclusion of the show's upcoming third season, which is currently in production, and will shift his focus to developing new shows for AMC, and potentially other networks in the AMC Networks…