I don’t think Kotick is at all certain to be kicked out. As easily as I can see MS letting him go with an enormous golden parachute, I can just as easily imagine them keeping him onboard because all they care about is Activision’s ability to make money.
In all likelihood Blizzard isn’t going to be managed any differently. Microsoft’s modus operandi with gaming acquisitions is to leave the leadership in place and let the dev/publisher run itself. Why is everyone expecting different here? The most likely outcome is MS does nothing to Blizzard and Blizzard continues on more or less the same trajectory as before.