Unless MacKinnon can develop a suitable powerforward-like game on the wing, he'd replace Stastny as our third center more likely. I think Drouin is the better winger for Staz simply because he is so elusive that Staz could thread a needle to Drouin who could deke out the last defender and get a breakaway.
Staz has no one like that sans Landeskog since Stewie left, Stewie would get open and Staz would find him at the top of the circles during an odd man rush and Stewie would just snipe the top corner of the net.
Staz needs either A. Powerforward with a high hockey IQ or a B. Sniper capable of generating a high degree of separation between himself and the defense.
If he can get a consistent winger of either variety he'll manage to revive his assists totals and people will stop riding him so hard over not scoring. Because he does everything else but get the assist numbers that he used to get when he played with Smyth, Hejduk, Wolski and Stewart.
You don't think Mackinnon fits this? Mack also plays somewhat of a hard nosed power type game.
I think Drouin would be better with Duchene personally.
Mack's stick handling ability goes unnoticed a little with Drouin around, but Mack can handle the puck in full stride much like Duchene can.
--------- Duchene - Parenteau
Landeskog - O'Reilly - Downie
--------- Stastny - Mackinnon
McGinn could take one spot, while we'd still need to find one more winger. Stalberg would fit as a big fast grinder for Duchene's line. Stalberg knows how to play with skill guys as well.
(I refuse to pencil Jones into the top 9 but one of those spots will probably be David Jones unfortunately.)
Stastny could also be interesting as a play-making left wing, if Mackinnon can learn to get good at face-offs and isn't transitioning to wing very well.
Edit : I wonder how much we'd need to add to Stastny to get Eriksson out of Dallas? Probably too much though, they weren't able to keep Roy and still need another top 6 center.