The fact is, Activision has not announced what exactly players will get for free and what they will receive for a premium price.
One thing is for certain, they have promised that playing the core multiplayer will always be free. Elite will offer 'services' that enhance the experience, but will not give a player any benefit in game over a player who is not a member.
So what are gamers willing to pay for? I don't think they are going to be paying extra for stat tracking. Too many sites already give this sort of information for free.