Activision has revealed the Call of Duty franchise has sold over 55 million copies worldwide after the release of.The sale figures means the series has earned Activision Blizzard over $3 billion USD in revenue with the latest hit Modern Warfare 2 estimated to have brought in $550 million in it’s .”Call Of Duty has become one of the greatest entertainment franchises of all time,” said Bobby Kotick, CEO of Activision Blizzard.He added, “If you consider the number of hours our audiences are engaged in playing Call of Duty games, it is likely to be one of the most viewed of all entertainment experiences in modern history.”The Call of Duty series is a massive franchise and forgetting the two Modern Warfare titles already had a massive following when you were put in the role of the Allied forces and fought the Nazis in World War II so it’s no wonder Activision has earned so much with the series.However you have to question where the company can go with the Call of Duty franchise now that Modern Warfare 2 has been released? In recent weeks there have been rumours a with Activiision keen on making a MMO based game on the brand. Maybe to keep the series fresh and sellable Activision needs to mix it up a little and that very well could be it. Let us know what your thoughts on the series are and IncGamers wants to hear what you expect to see in the future. Do so by letting us know in the comments section below.