According to NowGamer, WoW's Game Director Tom Chilton said the following to them at Gamescom 2013 regarding WoW going Free-to-Play:

Tom Chilton
I definitely think that free-to-play MMOs will be around for a very long time. At some point it's possible that World of Warcraft could end up being free-to-play, but I do think there's always room for there to be subscription games.

This is about as close to WoW going Free-to-Play as we have yet seen, however the intention is clearly there that Chilton believes WoW won't be doing so soon.

Read the whole topic over on NowGamer for more information... and keep in mind this doesn't mean the next expansion will bring Free-to-Play WoW, or that there are any plans for it to happen. Game Directors like to talk about possible futures, and that's all Chilton is doing (like any good Game Director should).

This article was originally published on WoW Insider.