Virtual Worlds

I feel that gaming/virtual worlds will still be around way longer than five or ten years. Developers keep coming up with more and more of these virtual worlds, so now more and more people keep joining them. Most people when they join these worlds they get addicted to them and want to play them more than they want to do anything else, plus normally belong to more than one of the communities. I feel like the best example of a virtual world would be the Sims video game. They are making so much money in this game because they sell it in many different game platforms as well as also selling additional packages that go along with these games. They keep coming out with new games as well so I dont see them going anywhere in the near future. But other free online virtual worlds I dont see how they will make it a long distance because the user is not paying for the game. So I feel like these kinda of virtual worlds could disappear or be replaced by other virtual worlds.