Cards... for D&D? Randomized? It's possible, but highly unlikely. If it does happen, they'll use the D&D Minis and Three Dragon Ante models.
As many of you know... D&D Minis is a collectible miniatures/card game. You don't need any D&D Minis whatsoever to play the RPG. However, the rules are heavily influenced by the use of minis... and D&D Minis sure are convenient. Again, I reiterate. D&D Minis aren't required to play the game. They don't add any new rules to the game, but despite that, I have a gigantic collection.
How could the D&D Minis model be used to create other randomized accessories for D&D? D&D Minis takes care of monsters. How about another card game that incorporated Spells and Magic Items. It could be completely randomized. On one side it would have the card game mechanic and on the other side it would have the D&D stats for that item/spell. There might even be cards for meta-magic feats.
Yet another card game based on the same basic mechanic could be made for Feats and Character Enhancements. I'm not quite sure how either game would work, but there you go. I suppose you could even combine it all into one game.
The other model, is Three Dragon Ante. Three Dragon Ante is entirely new accessory for D&D. It is not based on any D&D game mechanic that I know of, but it can be used as part of an RPG session. Three Dragon Ante is not randomized. A game like the randomized game I described above could be made with the Three Dragon Ante model. Again, it could be completely unnecessary for the RPG, but it could add a new element to the game. The bonus would be that the cards would also contain the standard RPG information on one side so that players and GMs could use them for easy reference.
One note about using cards for easy reference. People keep pointing out that it would be easier to just look up spells in the book. If I have a spellcaster and I have a standard set of spells that I use regularly... I just need to keep that subset of cards handy. I don't need the enire deck. Looking through a smaller set of cards doesn't take very long and I would say is faster than looking through the book.
As I said at the beginning... It's certainly possible that we would see some randomized card accessory, but I'm not in the least bit convinced that we'll see such a beast. Would I buy it? Probably not. I spend enough money on D&D Minis and Anachronism. That's all the money I plan to spend on collectibles for the next several years. WotC would have to make a very compelling argument for me to ditch either of those games.
--sam