CapFriendly has a pretty cool expansion draft simulator:
https://www.capfriendly.com/expansion-draft/seattleWith all of the big name players available, they could easily build a championship contender on day 1 if they wanted to, and likely add Owen Power to that (since it looks like he doesn't want to go to Buffalo).
As an example, I just made this team, with more than $20M in cap space to use to sign the FA's (although I know my team is unrealistic since they apparently want Driedger with one of their goalie picks):
Forward Lines:
1) Landeskog(UFA) Johansen Tarasenko
2) Hall(UFA) Domi Palat
3) Johnston Kerfoot Dadonov
4) Grundstrom Oglevie Barber
Defense Pairs:
1) Giordano/Zadorov (RFA)
2) Oleksiak (UFA)/Ceci (UFA)
3) Power/Hakanpaa (UFA)
Goalies:
1) Carey Price
2) Kaapo Kahkonen
3) Vitek Vanecek