Your question is a great one, however it only applies if you own your wallets (which most people do). It would not apply to wallets held with Bitcoin banks, like Coinbase, Xapo, Circlee, or Freebitco.in.
What ever you do, don't follow this guy's advice...
You could do what I did. Sell every coin you have and wait until the community gets their heads out of their asses then buy them back later, maybe.
The community has been debating whether and how to fork for over a year now. If you'd been out of the Bitcoin market for that long you'd miss all the appreciation of price we've seen over the last year.
A smarter move, if you're really worried about the coins setup post fork, is to convert your coins to a Coinbase, Xapo, or Circle account. They'll take of all of this for you.