It's not just an "end game" - the story needs to have a point. Conflict is just one piece of a narrative theme's resolution. Do they rebuild society? Does man devolve into a primal state and as the remembering generation dies off is all knowledge lost like the library at Alexandria? What part of the human soul and spirit survives and how is humanity changed? And how much longer can millions of rotting zombies sustain themselves (they should be piles of decomposing goo by now)? Why is no one even bothering to look for a cure anymore, and what does that say about mankind?

Also, while the show runners decided to rush the end of Game of Thrones, there was always a planned end to the story, and it's going to catch a lot of people off guard, because apparently the overwhelming majority of the fans watching it do not understand the point of the story. There are a host of consistently in your face but not necessarily spoon fed themes that will reach definitive resolutions that ultimately give the entire story a "point"; that is, if the show runners don't blow it.

I'm fully aware of the Kirkman comics. Just because it is a comic series doesn't mean it cannot or should not have an end. There have been several series that did, and many of them were good. Starting back in the 80s, I remember reading The Watchmen (also thematically loaded, and with a definite "point" to the story, for which it won many awards), and even something more serialized but definitely thematic like The 'Nam (84 issue run).