I don't think we (meaning the world) could go back to normal after Zday. The world's population would be few (probably) and people would have seen things they can't un-see. It would leave a lot of people scarred from the things they had to do or seen. I wouldn't be able to see the world the same ever again.
ZPOC = Zombie apocalypse.
Apocalypse = End of the world, not as we know it, it is the end full fucking stop.
in short, no the world would not be the same, nor would it ever return to normal
honestly i usually am, but when someone says apocalypse i take it's meaning seriously.
if they had said Pandemic that would be a completely different story, i'd reference things like the black death and the like and make some heroic speech about how we'd fight back and recover...
but lets face it, when the end of the world comes, we're all fucked, i plan to be having a fancy dress garden party when it comes, suits, ties the whole shebang
more to the point i just like people to use that thing called Language properly, and understand the meaning of words... is it too much to ask?