I do feel like it is inevitable because profits for MMOs are leaning heavily on the bonus content that costs money, rather than a monthly subscription fee. Guild Wars, for example, was always free to play, but they are able to make money off of micro transactions for vanity items on high level players. Given that Blizzard recently (within the last year or two) began introducing paid vanity items in their online store (pets and mounts mostly) it means they are also preparing for this inevitability. In my mind, the change will be gradual. They set up a free to play model for new players from level 1-20 and my guess is they will just slowly extend that level cap. Maybe in another year we'll see it lifted to level 30, then 40 after that. Right now the game is still profitable as a subscription based game because the player base is still ridiculously large (if you lose a million players and still have the population of a small country, it isn't time to change your model yet.) Plus, since The Old Republic launched as a subscription game, it means WoW isn't the only one doing it and the pressure to convert is lessened. I predict the game will finally reach full free to play a few years after they release its last expansion.