Not sure why anyone would have RNH as a the first center of the young star team. Against harder competition, RNH needs to be lower in the lineup. (RNH vs. Crosby, Toews, Malkin, Backstrom, Kopitar, are not favorable match up.) I'd much rather have Galchenyuk play in the middle overall, at least he would have a shot at competing physically, he's much harder to play against. Also let McDavid -Eichel have their Lemieux-Gretzky moment, McDavid will already be the first center by default from what I'm seeing in the early season. Huberdeau is the equivalent of a "vet" to play with the 2 phenoms. Saad is the competition there.
For these kind of world championships, pre-established chemistry matters:
1) Don't discount the possibility of MacKinnon-Drouin, even if Drouin is taking some time to get established in Tampa, the lightning is a great team.
2) Domi-Duclair if they keep playing like this are a must have duo and RNH might well be their perfect center.
3) The fourth line is an interesting question. Depends what is the mission. You could go for size with Scheifele - Monahan - Larkin or even Scheifele - Horvat - Monahan, or skill with Gaudreau etc.
Not sure exactly where Saad fits in honestly.
Huberdeau - McDavid - Eichel
MacKinnon - Galchenyuk - Drouin
Domi - RNH - Duclair
Gaudreau/Scheifele - Monahan/Scheifele - Larkin/Gaudreau
Bo Horvat / Saad / Couturier
There's probably 6 good lines competing here.
Murray- Ekblad
Rielly - Jones
Beaulieu - Trouba
Gibson