I can see TF2 going free-to-play mostly because of the fact that it was released years ago and the whole hats monopoly Valve has in the game basically pays for itself and more. As for DOTA 2, I think there would be a huge outrage if Valve went F2P-but-with-microtransactions, even if the paid content was just hats or costumes. Of course, Valve is Valve and they work in mysterious ways, so DOTA 2 is probably the free-to-play. Of course, this could be some enormous tease just to show that Valve didn't forget about Alien Swarm [http://store.steampowered.com/app/630/]...