There's not too many centers available, I could definitely see Seattle taking McCann.
Gourde, McCann, Jarnkrok and Tierney down the middle is pretty good depth. None of them are necessarily great, but they're decent enough. My guess is Van Riemsdyk, Zucker, Blackwell and Benson on the LW and Bailey, Donskoi, Appleton and Fischer on the RW. Their defense is going to be what makes them competitive.
My guess is Giordano, Simek, Dunn, Kukan, Stetcher, Bean and Clifton. Not to mention Fleury will most likely be in the mix as well. I could see them picking Bishop and Driedger as their goalies, but wouldn't be shocked if they get Kahkonen too. I don't think Seattle will shock the world like Las Vegas did, but I definitely think they'll be competitive. Their biggest weakness will be center, whether or not Gourde and McCann can be consistent top-six centers or not will depend on how far they go in my opinion.