I'm gonna go off the board and say the youngest ever to play in Olympic hockey for Canada, Nathan MacKinnon. Why? Duchene is on the team, yet when you compare their head to head numbers, MacKinnon has more goals and a better plus rating (+12 to Duchene's -1). Not to mention, MacKinnon has done most of this on less ice-time and 3rd line duties. He's also one of the fastest skaters in the NHL period which would service Team Canada well on the big european ice.
MacKinnon also has more goals than E. Staal, Neal, or Giroux. He has a better + rating as well than all of them (+21 better than Staal, +13 better than Giroux).
But hey, I know he won't get picked for sure as he's just 18. Just thought it'd be fun to put this out there and give the kid some props. I'd personally have him on the team simply for being top 5 fastest skater, goal scoring prowess, one of the best releases already in the NHL, and already one of the better defensive forwards in the NHL too.