I've just realised that when (and not if) it happens it won't last that long. One thing these films and series don't take into consideration is the the zombie brain. Once someone dies, they became a zombie. The only way to kill them is to destroy the brain or sever the brain stem, right..?
But once they're dead they start to rot. So that means that the skin and organs, including the brain, start to rot too. And once the brain rots that's one dead zombie. So then all we need to do is just relax with a few year's worth of food and supplies and it will all be over.