A little theory of mine.
Supposedly now what people are saying is that the game is a prequel and will feature Ghost. At this point most will flame and bash that idiot and yell at him that he died in MW2.
True. But if you notice during the "England" reveal section of the reveal trailer, there's police cars in the streets. During any such mass invasion, police would indefinitely be forced to retreat and focus on evacuating civilians and such so that the Armed forces could properly focus all attention on the enemy. It would make perfect sense that these England missions take place pre MW2, although whomever they were looking for or what they were looking for remains a mystery as in MW2 the entire game apparently took place over little over a week if not less, leaving the characters such as ghost no time to do other missions.
As for something else for thought. I can't find the source or quote, but apparently it's already been confirmed that quickscoping is back, but thats obvious. All 4 of the sniper rifles that have been confirmed are semi-auto so far and hopefully aren't the only ones.