By Call of Duty player, I assume they mean the people who play multiplayer? Or the single player type? There are 2 kinds.
Apparently, a huge number of people buy CoD for the sole reason of single player, according to one of the developers or something like that.
So, that's the single player type -- the person who wants to enjoy an adventure of sorts.
Then there's the multiplayer type, the one who enjoys the competitive nature of games. They enjoy competing against other people.
How does this game fit either of these 2 scenarios? It's going to be an MMO type of open world game, where people fight against zombies and perhaps other players. It won't be a first person shooter, or have a heavy focus on competing against other players.
Oh, and of course, they won't abandon the old fans! Even though it's nothing like the previous games that fans enjoyed.