Huntsman is a decent guy, but he was never in this race for real. The media adored him (because they love moderate Republicans during primary season), and that's about all he had going for him.
Romney would never make him his VP. He's viewed as the centrist Mormon candidate. Why would he put another centrist Mormon on the ticket? He's going to put a conservative on the ticket, but I think it'll be somebody who's not one of the current candidates. I think Romney will also be smart enough to put someone with a brain on the ticket. He's not going to pull a Sarah Palin.
Secretary of State? Very possible, and Huntsman would be a very good choice.