Prices will come down significantly, but not 75%. Don't kid yourself, ammo isn't immune from the same market forces that are driving down gas prices, such as reduction in raw materials costs, and decreasing demand.
Over the last couple years ammo prices have spiked, and most shooters I know are using less ammo and shooting more rimfire to stretch their dollars out. With raw materials and transportation prices falling, ammo prices will follow, but it will take some time. Remember that ammo manufacturers buy their raw materials on contract, and the ammo you will see on the shelf in the near future was produced at a price point based on the old contract. It will take a little bit of time for the price drops to filter down.
When you factor in the overall crappiness of the economy and people watching their 401ks and IRAs vaporize, I'd guarantee demand is down as well. Once the fat government contracts dry up for the ammunition manufacturers now that Iraq is getting quieter, you will really see prices drop as manufacturers try to keep excess plant capacity busy.
Oh yeah, and if people would stop ooohing and ahhing over a $350 case of 5.56, that would help prices come down as well. I refuse to pay that much for 5.56. Until prices come down, I'll make do with reloading cast bullets for my .45 ACP handguns, and shooting rimfire.