Doughty is going to make the team based on reputation alone. Team Canada always has those "reputation" selections, and Doughty will be one of them especially given his 20-21 season.
Chychrun is probably definitely on Canada's radar, but let's not forget that Team Canada takes international play into account when making these teams, rightly or wrongly. And as of now, Chychrun has only played U18 for Team Canada while Chabot has played U18, two World Juniors and two World Championships. He's "known" to Team Canada.
Lastly, I don't think Darnell Nurse will make the team. I think players like Theodore, Pelech, Chabot, and Reilly are all ahead of him on the left side. I also don't believe he'd be a good partner for Makar at all. Nurse is a rover to the extreme degree, the last thing Canada should want is arguably the best offensive defensemen in the league being paired with a guy that wants to do all of the offensive heavy lifting in Nurse.