Is there going to be a mw4

I think they will take a little break from Modern Warfare for a while because at the moment it seems like a little nag seen as all of the Call of Duty games are set at present or modern times.
It definitely won't be released (if there will be a MW4) in 2013, but possibly 2014/15 they may bring another CoD game which features the characters from the trilogy.
But for now, all they will be releasing is some DLC for MW3, so enjoy the game and worry about their future release when they mention it!