I think the commanders would stay there 15 years if we let them. Obama has told them from the start that he has no intention of doing that.
There have been some conflicting statements from Robert Gates, who as you know is leaving his long tour as Secretary of Defense at the end of the month. He has been quoted saying we should wrap up the "wars of choice" in Iraq and Afghanistan so we are fully ready for any "wars of necessity" that might arise. He has also said he favors a more gradual troop drawdown than the one advocated by the White House and some members of Congress.
Interesting article here -- pretty open and vulnerable for a man of his background.