That is the conclusion of this study by a professor of political science. The deciding factor will be this:
"If the United States were able to fight the entire war in the open desert, then our prediction of the war's length is 3-4 weeks," Bennett says. "However, the coalition forces have already had to turn their attention to cities in Iraq, and indeed, Baghdad is the primary objective. In a mixed environment of open country and urban terrain, our analysis suggests that a war will last two and one-half months.
