Actually.. the SWTOR case isn't unique to the mmo genre.
Lord of the Rings Online
April 2007 - LOTRO becomes the best selling PC game of the year
December 2007 - LOTRO dwindles but holds steady at 300,000 subscriptions
September 2010 - LOTRO becomes free to play
http://westkarana.com/index.php/2007/12/22/is-lord-of-the-rings-online-a-failure/
Age of Conan
June 2008 – AoC launches, sells over 1 million copies
February 2009 – AoC drops below 100,000 subscriptions
May 2011 - AoC becomes free to play
http://www.shacknews.com/article/57362/funcom-loses-23m-age-of
Warhammer Online
October 2008 - Warhammer reaches 750,000 players in less than a month
January 2009 - Warhammer's subscriptions dwindle to 300,000
November 2009 - Warhammer launches its "Endless Free Trial"
http://www.maximumpc.com/article/news/warhammer_online_slips_300000_subscribers_layoffs_rumored
Aion
September 2009 - Aion becomes the best selling PC game of the year, 400k pre-sales and 1 million units sold on its western release
Now - Aion has 3.5 million subscribers in Asia but faces dwindling numbers in the Western World which has never reached even 1/3 as many subscribers as Asia
http://www.gamespot.com/news/aion-preorders-near-400000-6228635
http://en.wikipedia.org/wiki/Aion:_The_Tower_of_Eternity
Rift
March 2011 - Rift launches, sells just over 1 million copies
August 2011 - Trion opens Rift free week, rumoured to be an attempt to boost dwindling subscriptions
Now - Trion has suspiciously never stated actual subscription numbers, but instead chose to "boast" that they took (a measily) 600k subscribers of WoW's then 12 million
http://news.mmosite.com/content/2011-06-08/rift_has_cost_50m_sold_1m_units_and_taken_6000000_players
_from_wow.shtml
Star Wars: The Old Republic
December 2011 - SWTOR launches, sells just over 1 million copies
http://latimesblogs.latimes.com/entertainmentnewsbuzz/2011/12/star-wars-the-old-republic-game.html
All those big titles had pretty similar beginnings.
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