In the past two years, quite a few MMOs have been making the transition to F2P with, apparently, great success. Recently, En Masse Entertainment
Last year, BioWare's Star Wars MMO The Old Republic was struggling to maintain a stable player base. In 2012, the game sustained a 400K drop in players from February to March, just a few months after its official launch. The losses were heavy enough that by August, BioWare and EA were already considering making a switch to free-to-play. The transition was finalized in November last year.
Now, SWTOR is reporting that over two million new accounts have been created since the F2P change. "Since launch of the free-to-play option we have had over 2 million new accounts created and have thousands of new players jumping in every single day," said BioWare executive producer Jeff Hickman in the SWTOR "State of the Game #3" blog post. "This means more people to play with, more growth for your guilds, more Warzone matches, and more ways for players to continue to advance their characters."