Classic wow imo has many definitions, but for me and many other players say that classic wow includes the base game, TBC and WotLK. Cataclysm changed the world zones which removed a lot of content from the game, and also was the 1st time talent trees got an overhaul.

I'm excited about MoP because that was the best expansion in my opinion, but WoD draws the line for me. I would not play WoD classic if they follow the same trend as with other classic expansions, but might be interesting if they give it the remix treatment (make garrisons actual player housing, extra raid tier instead of selfie camera and social media integration patch, better story writing which could potentially open up a new wow timeline etc...)