Has World of Warcraft stated how many expansions they intend to release or are they just winging it

Blizzard Entertainment is notorius for not releasing too much information about future patches and expansions. The only expansion that is confirmed is Cataclysm, which is close to being released to closed beta (it's in Friends and Family Beta at the moment and is under a Non-Disclosure Agreement [NDA]).

There has been speculation/conjecture/theories as to how many expansions there will be, but nothing is confirmed by Blizzard.