I'd probably think about something like:
Stamkos-McDavid-Point
Marchand-Crosby-Scheifele
***-MacKinnon-Marner
Stephenson-Thomas-Stone
***Would be one of Dubois/Konecny/Verhaeghe/Barzal/Nuge/Horvat/Mercer. With a second from that bunch as the "spare". Though
if Huberdeau bounces back, he'd immediately vault to the head of the line for that role.
Toews-Makar
Morrissey-Pietrangelo
Theodore-Doughty
*Reilly/Pelech
G: Hart/Jarry/Kuemper/Thompson.
Ughhh.
I'll catch flak for that 4th line and someone like Stephenson in particular i'm sure. It's not just taking the highest scoring, most productive players. But Canada has the luxury of insane depth of talent...which means we can start to thing about roles, chemistry, etc. We've seen before that it's important to take a good mix, including some "spare parts" that can play a checking/energy line role or plug into different spots as needed. As well as thinking about killing some penalties, rather than just loading up on powerplay guys when only ~10 of them will get any real opportunity to play there. Heck, we've had times where our 4th "checking/energy" line with Richard-Toews-Nash was our best unit at big moments and critical in getting the ball rolling.
I think two defensively responsible speedsters like Thomas and Stephenson would really complement someone slow like Stone. They're also the sort of useful players who could plug in elsewhere in the lineup if the chemistry is all misfiring and you just need a simple "get in on the forecheck" sparkplug to jumpstart a line. They've both got loads of positional/role versatility and that's valuable. Especially in the sort of players who could potentially play "4th line" minutes, kill penalties, and still be effective. Stephenson in particular to me, is like a supercharged version of that proverbial "Swiss Army Knife" type player who can do a bit of everything, plug in pretty much anywhere, and not look out of place. Tons of big game playoff experience and clutch as heck. Who knows, he could probably even play the "Hyman role" with McDavid if things aren't working, or fill in beside MacKinnon. I think that flexibility is invaluable in a tournament where chemistry is such a big guessing game with zero time to figure it out.