Re: World War Z ratings/spoilers
Eh, a sequel can always handwave away the camouflage if they want to - "the zombies adapted; time for a new strategy."
There's plenty of ways to go, the idea seemed to be to more use the camouflage for soldiers or people in battle (maybe in extreme circumstances people in isolated areas that couldn't be protected like the villagers we see during the coda.) But even with this "camouflage" there's still danger to civilians or people not "infected" and it's still possible the zombies could adapt to it or still pose some level of threat to even those camouflaged like getting caught up in "zombie crossfire." There's a direction they can go with it without writing it completely off or trying to retcon it away.
Just because it's futuristic doesn't mean it's practical.