2.) Call of Duty
Now, it is highly unlikely Call of Duty goes exclusive because of how passionately vocal their fan base is and more importantly how much of a cash cow the franchise is especially on multiple platforms.
However, I believe that it would be very beneficial for either Microsoft or Sony if it or any other shooter on the same level was made into an exclusive. It could backfire though as people might flock towards another multi-platform shooter.
I think that Microsoft would be the company who would benefit the most since they have the power to make cross-play between PC and Xbox possible. It caters to a wider audience and it lets players play with more friends and strangers.