I'll give you an answer for each of he big four, AND how it would happen.
Russia: Tarasenko one time laser. Most likely on the PP. His shot is pretty much elite right now when given a good chance, I think him losing the D to set up some free space leads to a huge blast.
US: Got a weird feeling if a US player does something great, it will be a defensemen. I think i will be either McDonaugh, Martin, or Faulk, but I'll say Martin. Point shot with traffic in front. Maybe bangs of a defender leading to a "flukey" goal that is more set up by good team structure. If the US is gonna win games, it will be based around that.
Canada: Probably Crosby again, just cause god forbid someone ELSE becomes a golden boy. Ended after Canada keeps even strength possesion of the puck in the opponent zone for a long period and the D wearing down. Won't be a highlight, just Crosby being in the right spot and reading the play.
Sweden: Backstrom scores one of his blue moon goals, after the goalie buys pass on a 3-2 and he instead shoots high glove.