Though it's still one of the most popular shows on television, over the past year The Walking Dead has undergone a radical transformation. With ratings falling, a two-year-long storyline wrapped up and rampant rumours that Andrew Lincoln will be leaving (alongside a few other series regulars) in season 9, the current state of affairs has resulted in many fans looking for a way to wrap the show up before it nosedives completely.
With Rick almost certainly exiting the programme in one form or another come the end of the year, the writers are going to have to come up with something special if they want people to stick around. While the comic might be bigger than Rick, the show certainly isn't, and him leaving could offer a rare natural endpoint that might not be so easy to produce in a few years' time. Especially now that there's no Carl to carry on the lineage.
AMC themselves have always thrown around a 12-season goal for the series, but with so many radical changes being made between 8 and 9, it might be a better move to start thinking of an end now, unless they want to be doomed to end up like one of the lifeless shamblers found in the show itself.