WoW has infinite difficulty basically, if you really want a challenge start playing and try and catch up. The game barely even starts once you hit the max level.. there is a LUDACRIS amount of content, enough to keep you occupied for years. Always something fun to do. Even if you get to the highest echelons, which is doubtful unless you really go for it 12 hours a day

, the hardest bosses are still fun and difficult, and they add more. New expansion coming soon will make that even moreso.