It's been almost two weeks since the 21.3.0 patch arrived which featured nerfs, buffs, changes, and a card ban in wild. With that in mind, you have around 2 days remaining to decide if you should get a full refund for the cards that were nerfed or changed in the patch. No better time for that last search of your collection to see if there is anything relevant still hiding in there. Soon the following cards will no longer grant you the full amount of arcane dust upon disenchanting: 

The above cards will all remain disenchantable for full arcane dust value through October 5.

When Blizzard offers dust refunds for nerfed and changed cards, they do so for two weeks following the patch. We always recommend getting your dust as soon as possible though so you don't forget to take advantage of the situation.

New Feature: Refund Keyword in the Collection

When Patch 21.0 hit with preparations for United in Stormwind, a very important feature was added to the collection manager. No more do we need to manually go looking for refund-capable cards because Blizzard added in a new keyword that will find them for you.

By typing "refund" in the collection manager search box, you will now be able to find these cards together and make your decision on whether or not they are getting dusted. An excellent addition to the game that unfortunately took this long to make happen. It doesn't matter though, we'll always take a quality of live improvement and as they say, the second best time to plant a tree is today.

Quote From Blizzard

Searching “Refund” in the Collection will now populate with cards eligible for a dust refund.