I don't see a double minority ticket being pushed. Richardson is a horrible debater as well, and more importantly he's not an attack dog.
The "change" mantra has been replaced by a need for experience. Change worked in the primaries but voters are more concerned about who they can trust, who has the better track record, and who's energy policy is best among other things. If he chooses a "change" VP like Kaine or Sebelius we'll just be hearing about how in-experienced the ticket is. I'd rather take a bullet on experience than take one on change