I don't see Bergeron being named captain mainly because he's never played in the tournament. I would be shocked if the captaincy was not given to one of the returning players.
Can someone name a previous season (other than the first WJC obviously) where the captain was not a returning player?
Another smaller point is that Bergeron is still not exactly a dynamic personality when he's speaking the English language; in fact, any interviews I've seen with him have been snoozefests. There's a good chance that Bergeron will be the only francophone on the team; I doubt that sutter would give the captaincy to the sole francophone - just my guess. I expect Bergeron to be a quiet leader; as he's played with very few of his teammates before.
I think at the pro level, the captain can let his play do the talking (a la Yzerman, Sundin, Naslund, etc.), but for a world junior tournament, I believe it's improtant to have a captain with a bit more of a 'rah rah' attitude.
Richards or Phaneuf would be my first choices.