Much of what U.S. service personnel died or were wounded for will have been lost. Although extremely tragic, however, this bad outcome may not be the worst effect of the war. That would be the destabilization of nearby Pakistan, which has 100-200 nuclear weapons and an insurgency trying to overthrow the Pakistani government.
The candidates must accept the final results of the runoff, and remain open to working together in the next government. If the loser feeds a frenzy of public opposition, it could lay the groundwork for something like the civil war that tore the country apart and opened the door to Taliban rule in the 1990s.