I disagree. I think that our enemies just need an excuse to kill us. Iraq or Afghanistan or badly drawn cartoons will incite our enemies.
Further, with the Iraq War all but won, our anti-war side will quickly lose their enthusiasm for the Afghanistan War since that support was only about providing cover to advocate losing in Iraq. Without the greater objective of losing Iraq possible, the reason to support the Afghanistan War is ending. So Afghanistan is well on the way to being the "bad" war.
And our Left will have even more reason to hate the Afghanistan War since our enemies will use this war rather than Iraq to justify killing us:
This week's brazen and deadly attack on a US-Afghan outpost in an area near the Pakistani border is raising new concerns that foreign fighters bent on fighting the West are retraining their sights from Iraq to Afghanistan and Pakistan.
I know this is inconvenient for our anti-war Left, but they'll adapt and oppose the only war they've got to hate.
UPDATE: Look out, Moslems are incited by the "good war":
More foreigners are infiltrating Afghanistan because of a recruitment drive by al-Qaida as well as a burgeoning insurgency that has made movement easier across the border from Pakistan, U.S. officials, militants and experts say. For the past two months, Afghanistan has overtaken Iraq in deaths of U.S. and allied troops, and nine American soldiers were killed at a remote base in Kunar province Sunday in the deadliest attack in years.
If our enemies hate us enough to fight us over Afghanistan, our Left will agree with our enemies that we are provoking them by fighting in Afghanistan. This by definition cannot be a good war for our Left.