I really hope a big gaming company like blizzard would use crypto-currencies as their in game currency in the future, if Blizzard would use crypto-currencies instead of gold for one of their famous game Diablo, I believe there will be a lot more players playing it as there is a potential to earn some money while enjoying the game with friends.
This is a really bad idea, people should stop trying to apply Bitcoin and blockchain to literally everything and instead ask the questions "does it solve any problems?" and "how does it compare with other solutions?". So, lets imagine WoW or Diablo switched their gold to Bitcoin. First, from where it would come? Does that mean that Blizzard now have to reward each player for every killed mob with some dust amount of BTC? If so, they would quickly go bankrupt as they would just be giving money away instead of making them. Second, why should they put their in-game economy on the blockchain, if it doesn't give any benefits to anyone - players would have to face transaction fees and delays, and the company would lose their ability to control the market and punish scammers and cheaters.