In the short to medium term, losing does not necessarily mean that Shariah law is instituted in the United States, though that would certainly be incontrovertible evidence that we have lost. I think we can lose in many other ways, smaller but in the long run just as deadly; in the next 5-10 years, losing the war would include any of these possibilities:
1) Europe descends into chaos or surrenders to Shariah.
2) Tel Aviv is destroyed by a nuclear weapon and/or the state of Israel is effectively destroyed.
3) Western nations descend into chronic recession and depression because the price of oil reaches unbearable heights.
4) The United States surrenders to isolationism and abandons Iraq, Afghanistan, etc.
5) The worst case scenario is one in which the United States ceases to be a functioning Democratic Republic after a series of attacks which kill enough and terrify enough.
Now possibly these seem like extreme possibilities to you but consider that there are many who believe that:
The United States economy, as currently constituted, cannot maintain itself without an international enemy. The defeat of one enemy, Soviet Communism, did not result in a "peace dividend." Instead it led to a desperate search for a new enemy to justify a continuation of the Military-Industrial-(Political-Academic-Media) complex. Then Osama bin Laden, al Qaeda and "Islamo-Fascism" – George Bush’s “Axis of Evil” – obligingly stepped forward to fill this role. And so we continue to build multi-billion dollar aircraft carriers and submarines, and an unworkable missile defense system, and we have reinvigorated our atomic weapons program, to fight the new enemy: fanatics armed with box-cutters, and armed brigands hiding in the caves of Afghanistan and Pakistan.
So long as self-defence is regarded as unnecessary, we are in serious danger. Read Shrinkwrapped here and the moonbat here.