I didn't enjoy a lot about Cataclysm (a lot of disappointing raid bosses, Dragon Soul was terrible, didn't like the healing model) and I just wasn't excited about MoP - the story didn't appeal to me, I would have not been happy on a PvP server with the leveling/flying restrictions but didn't want to look for a new guild, didn't think healing was better, and wasn't confident the raids would be fun. I am still interested in certain parts of the storyline. I would consider playing an expac focused on some of the storylines I enjoy like Burning Legion, Azshara, Old Gods, etc. I'm not sure whether I'll be able to raid hardcore though for a couple years due to real life responsibilities (first child) and I don't really enjoy casual play very much, so it would have to be a really interesting expac concept to get me back. I would definitely play a WC4 if it was ever released. Before quitting I had played for six years and cleared almost all content when it was relevant, so I was pretty hardcore for a long time and I don't think I'd want to spend a lot of time playing again unless hard core raiding is an option in my life.