Considering the teams stay at the positions they are now: (not taking into account possible refusals or injuries)
Goaltenders:
Luongo, S.Mason, and Bernier would be my choice, or at least one of them

Others in the mix - Emery, Smith, McElhinney, Ward, Reimer.
Defensemen:
Giordano, Brodie, Vlasic, Burns + (Ekblad, Rielly?), others in the mix -
Daley,
Barrie, Wideman, Phaneuf.
In offence, I wouldn't hesitate to take players like Stone, Kadri, or Couturier, but there are many options. You have players like Monahan, Duchene, Hall, O'Reilly or J.Staal. Cammalleri has been playing well. I like Simmonds for this team and think he gets a spot if he says 'yes'. JasonSpezza and Eric Staal are questions for me, but I personally think there might be a chance we could see them in May playing for Canada. What about Nugent-Hopkins? Kyle Turris? Players like Hartnell, Henrique, or Huberdeau might be an option if there's a lot of refusals. Cody Eakin and Jordan Eberle might get an invitation.
Forwards:
Benn-Spezza-Seguin, Duchene-Giroux-MacKinnon, Couture-E.Staal-Johansen, Cammalleri-O'Reilly-J.Staal, others in the mix -
Simmonds, Hall, Monahan, Kadri, Turris, Couturier, Nugent-Hopkins
I don't see more like 5-6 changes on that roster (if the availability of the players stays the same). It will be a strong roster imo. I personally even think Giroux and Seguin will go.