If it was trading in gold for war nickels, I don't think that I would go for it. The problem is that war nickels are:
A) Illegal to melt down. Despite popular belief the law says it is illegal to melt down -all- 1 and 5 cent pieces, there is no special exemption for war nickels (or even half dimes)
http://www.usmint.gov/pressroom/index.cfm?action=press_release&ID=724
B) Are not likely to be recognized by the general public in the event of a currency collapse, most people think that the nickel contains... nickel, and convincing the general public that nickels made from '42-45 contain silver might be next to impossible, especially with the breakdown in society that would come with a currency collapse (as in, no internet, no libraries, etc.)
C) They trade at such a discount to silver content. Even if the melt ban was lifted, the fact it isn't pure means refiners charge extra for melting them down. While at this time there is enough collector demand of bullion and junk silver that it would be silly to melt it down (after all, if you can get it for $2 less than spot, and sell it for $2 more than spot to a collector, why pay refining fees?), in the '80s, long lines at the refiners and low demand from the general public meant that coins had to be discounted because they weren't sure when they were going to make it to the refiners.
If you want to get silver, I'd try sniping some silver mint sets or proof sets off of eBay with the cash you get from selling your gold on the open market. While War nickels are great to get for 5 cents while CRHing, and fun to make a set with, you'd be better off getting 90% pure coins, or just generic bars/rounds.