Sega kind of telegraphed their punch here a few weeks ago when the AvP page went up on Steam, as pre-purchasers get some unique kit for their characters - clearly DLC was part of the games future and they were almost certainly not going with the universally loathed GFWL so Steam was pretty obvious (and they were never going to come up with their own system for DLC).

I feel sorry for people who like to sell games when they're done, but for me this is a good move, I like Steam. For those who like to get some financial return when they;re done with a game, perhaps they can just wait a little while till it's significantly cheaper (and patched) in a few months time.