During the Playstation 2 Era, resident evil had a four player co-op game called Resident Evil Outbreak. This is what Left for Dead actually copied but they made it more action/arcade like, while outbreak was more of a multiplayer/puzzle/action game.
Should Capcom come out with a new PC only verion? Or even for consoles?
I don't think such franchise would ever make a PC only title. However, they recently came out with a coop (2 player) game for the Wii exclusively. Resident Evil 5 was also available for both the PC and consoles (2 player coop).
Will they take the jump to 4 player coop on their next title? They would have to calculate the cost/benefit of adding 2 additional players. RE series have their own genre (far from L4D), and the producer will take to account that RE would or would not make sense to have 4 player coop.
In my opinion, you can't make a serious horror game (in such as RE series) with a 4 coop player option. So, will the producer decide to sacrifice RE' integrity for a little more coop action? I don't know.