Pavelski is both a lock and will be one of the most important Team USA forwards. Canada is tough because there are several teams you could pick out of that talent pool- do you go pure speed on international ice? Do you focus on two-way, versatile players or split between skill guys and grit? What mix of defensive responsibility, physicality, and puck-rushing do you want on the defense corps?
Couture seems the most likely to crack the roster simply because he slots into a lot of different frameworks. I think Vlasic looks a lot better offensively, and if he's on track for 40-45pts at the end of the (calendar) year I think he's got a good chance- especially if a couple guys get hurt. Thornton doesn't seem to have a role, and Boyle has to deal with offensive puck-rushers who are both substantially younger and substantially bigger.
The Euros seem pretty set, depending on if Havlat a) returns and b) looks any good.
Honestly I understand the selfish impulse to say "I don't want any Sharks playing in the Olympics because of injury/stamina things" but I think that's a bit heartless. A gold medal is a huge deal, especially when you're playing and beating teams that are incredibly talented. Personally while I'm a Sharks fan, I'm also a Sharks player fan. If Hertl goes and gets a bronze, I'd be jazzed. Yeah it's not the Stanley Cup, but you wish the absolute best of the people who play and try to bring pride to their family and their nation.