I've only given this a little bit of thought.
If it is the end of the world, fashion is going to be the very LAST in what you're thinking about. Unless, its for survival techniques. Specifically, intimidation and camouflage. There are always two kinds of people in post-apocalyptic movies: foragers, and hunters.
Then again, if you're a bad ass / cannibal / Queen, you've got to go for the intimidation route. Here's a good look to take inspiration from.
Tina Turner does good chain maille chic in Thunderdome.
Heels are out of the picture, because you have to be able to chase your prey,
but who says you can't have a little flair?
It's funny though, because studs used to be scary, but now they're not.
Face paint maybe? Nope. That's only scary in the sad way.
A swishy fringe jacket for intimidation. Anything that makes you seem a little bigger
than you are, not unlike the transformer owl.
Leather pants. Preferably.
Now, is this more survival friendly or Freaks and Geeks?
Sexy camo pants. You have to encourage re-population right?
Comfortable shoes are a must, preferably something that you can run in with treads,
for climbing big hills and running away from cannibals.
All clothes from Nasty Gal. Because I'm too lazy for this.