If there were to be a "Google Edition" of the GS4, then I imagine it would be like the I/O version of the Galaxy Tab 10.1, i.e. it will be a limited edition and not available to the general public.
That's just my guess anyway. Otherwise, it would be awesome if they made something like this available across all carriers...oh, let a person dream. As much as I like the stock experience, it's not enough to pull my away from my discounted unlimited data plan on Verizon. Otherwise, I'd be on a Nexus phone right now.