Team Canada in 20 games would probably be somewhere along the lines of 9-10-1 imo. Probably able to compete, but wouldn't dominate.
It would be a lot worse than 9-10-1. World Junior team would probably go negative vs top college teams. Keep in mind half of a world Junior team end up being busts or play in AHL/Europe. All top AHL players destroyed junior leagues. You have ppg+ players from junior who can't even make AHL teams.
Edit: I think this could change in SOME years where the Canadian team is absolutely stacked, but given an average year they would get destroyed. Aka 2010-2014 Canada teams. I mean Canada isn't even dominating the world Juniors every year, they are losing to teams like Sweden and Russia and Finland. On average they get destroyed by the AHL imo