Ravious from Kill Ten Rats observes that while MMOs typically demand more of players than standard PC games (at least in terms of time), the wide variety of gaming options that Steam users have come to appreciate could certainly be applicable to MMOs, if other business models beyond monthly subscriptions become viable in the West. Ravious writes, "Whether it is from a Steam-driven library of games, an aging MMO population, an economic recession, or plenty of different business models coming in to the MMO world, I believe that the subscription model of today is nearly done being 'the way'."
While some games are clearly worth that $15 per month, that pricing doesn't fit all MMOs on the market. That's not to say that they're bad games, or aren't enjoyable. But the fact that many games can be played for free does open up more options for the consumer.
Ravious envisions change coming to the MMO industry, where varying pricing models lead to a situation where "the new market winners are going to be the niche MMOs that try things a different way." He points out that an increasing number of games requiring less dedication than your AAA massively multiplayer title of today are going to be appearing on more people's radar, and that the more dedication-intensive MMOs will become geared towards a niche audience.
Ravious has some interesting views on a direction the MMO industry may take, which are only briefly mentioned here. Have a look at his "Tao of the MMO Gamer" over at Kill Ten Rats for his angle on change in the industry, and let him know what you think.