I would say that having this in game would be a dream for many players. It would bring in a lot of players who would love to have the freedom this would give players. Some really amazing games are using bitcoin blockchain tech already and have in game assets tied to the blockchain. Simply amazing things happening.
We'll work towards allowing as many external systems as possible, like PayPal, Bitcoin, and whatever other wallets players ask for. The whole idea is to keep it open and easy. If people want to spend real money to buy items from other players -- they can. And when this happens, seller can draw those funds out of the game.