Despite shrill articles such as this one from Bloomberg, the market probably has the reaction just about right which is that none of the stocks in question moved a whole lot on this announcement. Apple (AAPL) ran up in the last couple of months in anticipation of this, but didn't do a whole lot today. Neither did Verizon (VZ), AT&T (T), Motorola (MMI) or anyone else for that matter. I think that's because frankly there isn't the iPhone frenzy there once was and that those with existing contracts won't be that willing, or able, to switch immediately.
The article's assertion that half of Verizon users will switch from Android to iPhone seems a little ridiculous. I think that this was a classic case of an analyst not knowing so they just made something up, and something not particularly plausible. The problem that iPhone has in the long run against Android is that the Android universe of phones offers customers features in whatever configuration they might want. Additionally, in terms of hardware capabilities, by the next iteration of iPhone Apple will have to be playing catch-up big time against the new vanguard of Android phones.
There will be switchers, sure, but I just don't get the sense that the bulk of Android users are just clamoring to switch. No doubt, many AT&T users will switch, but that's a different story.