Exactly. If I see both have shipped, I'm going to look at going prices on Ebay and if I can make money (after subsidized) I'll sell it. If not, simple return will do.
With the delays getting worse, we may see the prices go up. Who knows though.
I think you're going to see prices hit the moon when you're posting up legitimate pics of an iPhone 4 on launch day available for overnight shipping. There are enough rich kids out there with daddy's credit card that I don't think you'll have a problem selling one for a profit even after you pay the unsubsidized price.
You just have to make the ad look legitimate, using pics with a piece of paper with your username beside the phone, etc. A lot of the iPhone 4 preorders I see on eBay right now look like total scams, and the ones that are legitimate are still based on the speculation that the phone will arrive on the 24th.