The big 5 will allways be the big 5 but their prices were exceeded by mythics ages ago and strength wise even longer ago.
As for the market Im ok with the decrease in prices. I can see how it could annoy investers, but thats just a risk you take when investing in anything, but for collectors and players It dosnt have too much of an effect, unless your trying to get mythics, because all non mythic prices are down.
@Ares: As far as I remember They announced that FR was closeing and stopped gem purchases along with new releases before the market was completely messed up. UR has no plans of closing.
Big 5 will always be Big 5, it's more than just price and power which makes these 'Big 5' they have been around since the dawn of time and have been a goal for many players for years. I do see your point though, they have been overshadowed by others cards in terms of rarity and power now, happens though as time goes on.