[Ed Zachary]

Let's see:
Android is owned by Google.
The Nexus is Google's foray into getting in on the branding/selling handsets action.

Now TMo lets you buy a (subsidized) phone from Google and activate it on their network. This requires an agreement with Google, including TMo cannot sell the Nexus in their stores. Google keeps the sales activity in their baliwick.

If (IF!) Verizon will let you buy a (full-priced) Nexus from Google and activate it on their network, I seriously doubt that Google would give up any sales to Verizon. Subsidized by Verizon or otherwise.
Sure, it may be an HTC Desire by another name, but it will be running Android so Google will have a lot to say about the sales arrangements.

That being said, we ARE talking about a couple of 800lb gorillas. As we know, that type of beast can change rules and arrangements whenever they feel like it.