The team in Seattle, will cause a natural rivalry with Vancouver, which is a good thing for the league. Fans from Calgary and Edmonton, will also go to Seattle to see their teams play as well. In addition, it will have an equal amount of teams in the west and east and the divisions will be equal as well. I like the fact that it is a team in a northern state. Most of the other teams in the southern states do not do well as they either have warmer weather or that they have other more hi profile sports like the NASCAR, NFL, MLB, NBA and NCAA. Hockey is most states ranks at or near the bottom.
I know most people were wanting Quebec to get a team, but the market in Quebec is already saturated with the Habs and also with several other original 6 fans. There is no room for growth. In Seattle, there is room for growth.
The other thing is TV revenue. There is more money in TV in the US then Canada.
The expansion draft will be the same as what Las Vegas saw. So, you are likely looking at a team that will be competitive right away as well. This is good for the league.
All in all this is a win for the NHL and the other teams.