Right. Apple is not going to stop making a GSM/UMTS version of the iPhone if they happen to come out with a CDMA2K+EVDO version. If they did, they'd have to abandon nearly ALL of their other carriers WORLDWIDE that use the exact same model of iPhone that currently works on the AT&T network. Not going to happen.
The whole reason that Apple went with GSM first is because initially they didn't want to commit the resources to making multiple different versions (and perhaps still don't want to...who knows? the "Verizon iPhone" is still a rumor at this point), so they aimed at the technology that had the most use/implementation by cellular carriers worldwide.
Not to mention that Verizon Wireless (who is owned in large part by Vodafone) has already announced that they will be switching to "4G GSM" (LTE) when they transition to their new 4G network. Apple may still decide to make an EVDO version of the iPhone for all I know, but unless they plan on selling it through more carriers than just Verizon, with the looming Verizon 4G network on the horizon, it seems to me that it makes LESS sense for them to make an EVDO version of the phone now than it did 2 years ago when the iPhone first hit the scene, since EVDO is that much closer to obsolescence now.
-- Nathan