No mw2 will sell more then mw1 (mainly because the love of the first is being transferred to over to the second game). If mw2 gets mxed word of mouth then it will more negatively affect mw3 then the current version.
It happens in movies all the time where the sequel does better then the first because of the love of the original and the third iteration doesn't do aswell because of the negative word of mouth from the second. Take the matrix trilogy as a classic example of this.







