The Walking Dead shouldn’t run in to the same sort of problems anytime soon that Game of Thrones did when the HBO epic reached the end of its source material.
Even if The Walking Dead as a show was beholden to the comics, the show still has a while to catch up to the comics.
(Take note, George R.R. Martin, and finish The Winds of Winter!)
Robert Kirkman is no George R.R. Martin, and he continued to publish new installments in his saga throughout the run of the show on AMC.