Face it, you have zombies, you have friends, you have an apocolypse, you have a shotgun (no ammo though). What more could you possibly want? (besides ammo)
Okay, back when the first 2 Outbreaks came out, they were poorly received, but online multiplayer was still at it's infancy and it was the first online co-op RE game ever.
After the massive success of games like Left 4 Dead, I really don't see how an Outbreak game could not work in this generation gaming.