http://massively.joystiq.com/2015/01/12/rumor-world-of-warcraft-may-be-prepping-a-free-veteran-editio/
This makes sense, especially with the announcement of buying tokens with real money and selling them with gold, and also the restrictions lifted on newly created DK's.
World of Warcraft dataminers, while diving into the piles of information for the upcoming Patch 6.1, may have found game-changing evidence that the title is preparing a new free-to-play option.
The data files include several references to a "Veteran Edition," in a similar fashion to the already-existing Trial Edition, which allows players to level to 20 for free. The Veteran Edition has several limitations listed, including a level cap, money cap, and chat channel restrictions.
There's a lot of speculation going on right now as to whether or not the Veteran Edition will happen, and if it does what it will entail. MMO blogger Superior Realities theorizes that WoW will allow subscription-lapsed accounts to continue playing with the above restrictions.
This makes sense, especially with the announcement of buying tokens with real money and selling them with gold, and also the restrictions lifted on newly created DK's.