Okay, so now I'm confused here. I'm becoming more and more sure that this won't have new characters and just use the original ones. They all look to weird/recycled. I think this may be more of an expansion, and Valve is just joking with us. They do that. If it is an expansion, it will probably still cost money, but it will probably not be to much for those who already own Left 4 Dead. If this is true, then NO ONE SHOULD COMPLAIN. People have WANTED new campaigns. This should be making people jump for joy. If this was announced as an expansion instead of a new game, they would be.
It's still confusing though. It just seems too quick. Also, I'm VERY sure that different teams work on different games at Valve. What does this mean? Valve isn't forgetting Episode 3. I'm wondering if they're supping up the Source engine graphically, and that's why so little is known (big surprise to see massive graphic changes) and why it's taking so long. This game obviously doesn't (if you see the gameplay footage). This is more likely the L4D team working on stuff. If it turns out terrible or whatever (doubt it), blame that team, not Valve as a whole. I don't mind paying more money... I just want it to be more like an add on. I've grown fond of the original characters.
Also, the axe is AWESOME.