Crafting Materials! How many you got? Will they become Worthless?

Personally i think nothing will change.

With this event they promote a new wave of skins and stuff tradable only by a currency that has been made specially for the Iron Crown. Actually did not really worked out and now the shop has been brought back to normal (currency and price-wise) so, we can easily assume that has been just a marketing move and that something like this will never gonna happen again so, no worries for your crafting materials!