The proclemation that the game is constantly going to adapt around the players current status does sound like an interesting idea (but then again, its a question of whether it actually works or not) but I'm raising eyebrows at the strong focus on team play to the extent that they have intended the game to casually kill off any player who decides to go off on their own for a quick killing spree. If there is one thing I have learnt from my time playing games online that is that getting a group of people who don't know each other to co-operate and work together is like expecting world famine to stop just because you put up a very pretty pink charity poster in your local library (in other words, it's probably not going to happen).
Imagine the scenario, you and your 3 team mates have just been gunning through endless hordes of zombies for the last 20 minutes, ammo is low, health is low and you are all wanting the mission/level to end soon. One of your team mates gets bored of following everyone else around and decides to go off on their own for a bit they get themselves killed. You are now left with only 2 team mates (making the game that bit harder), in short, I can only see this game leading to people getting very pissed with each other because 'you didn't follow the plan, n00b!'.
Another thing, survival based games revolve around fast decisions and co-operation. Every game will require one player to take the lead and boss everyone about (joint decisions would take too long resulting in you having to balance zombie slaying and the debate surrounding who gets the last rolo at the same time). What if the one guy/gal taking charge is inept (heres the plan, I go onto the helicopter to saftey while you guys die heroically to cover my escape...I'll tell the newspapers about you!) and just doing as you're told isn't going to be fun or entertaining for the other players.