If this is true, and I have my doubts, I don't think it will be a huge coup against droid. First of all, it will mean that AT&T will have incentive to expand it's selection of android phones. Now it has a monetary reason to downplay droid because so many people are on their network just so they can have an iphone. If they admit that android phones are as good, then they risk losing people who are only on their network for the iphone. If the iPhone leaves, AT&T loses that incentive and I can guarantee you'll see an expansion of droid phones on AT&T along with AT&T pushing Droid phones. In addition, you'll see price wars with droid phones in a better position to offer discounts while iphones on Verizon will encounter shortages and delays (as they already do even being limited to AT&T).
More then that, nothing has been confirmed. And every article so far talking about the iphone migrating has been filled with here-say and speculation. What little evidence there is, the contract between Apple and AT&T goes through 2012. Of course there are ways for that contract to end, and I'm sure Apple is nervous that their market is limited by the carrier. But it doesn't mean the end of the world for Android.