Re: Subban's lack of playing time for Team Canada, I got the feeling that Subban was a player who could really carry the play and dominate against average players, but didn't stand out as much with or against the best. That's how he won his Norris in 2013, playing weaker opposition and dominating play.
His peers Doughty and Karlsson, who were at their best when playing with and against the best players. While Karlsson rarely had the chance to play with top end offensive talent in Ottawa, he and Jason Spezza had a special connection in the 2011-12 season where you could tell they were both seeing the game at a higher level than anyone else, and they could find each other anywhere on the ice. I also think of the way Karlsson stood out on a skilled Team Sweden in 2014, even though his mobility wasn't fully back after the Achilles injury, and the way he always stepped up defensively against Alex Ovechkin. Doughty has long had a rep for coasting in the regular season and then bringing it in the playoffs as well as international play. Subban was consistently effective in the regular season, and showed in 2018 that he was a valuable player in a playoff setting as well, but I don't know if he would have been as good as some of his peers in a Team Canada type setting.
Maybe there's a place in the HOF for his 6 year peak as very effective and entertaining defenceman. Certainly a peak Norris finish of 1-3-3 is a good start for a HOF case. I would say though that while he may have deserved those awards for his regular season performance, I think they overstate his place among the top defencemen of his generation. I don't think he was ever the best, and maybe not top 3 either, when you look beyond the regular season to include playoff and international play.