I have to believe their extensive testing makes them believe they can't meet their advertised 30 MPG. Rather than have numbers behind the Ford Ranger, they will wait for the 2011 Unibody model. It will be lighter and they should have time to tweek the transmission to get the needed MPG. Of course it could be something else.
Those who can wait will and those who can't will move on. I am sure they can find buyers regardless of the release year.