NHN, the publisher of the Japanese & Korean versions of TERA, has announced that all servers will be converting to a free to play version in early 2013. Korean TERA servers will see F2P action on January 10th, with Japanese servers heading that way in mid-February.
There is no word from either En Masse Entertainment (NA version) or Gameforge (EU) about whether or not they will follow suit.
Read more at MMO Culture.