Shamrock....
Interesting thoughts. I guess I don't quite interpret things that way. I would interpret like this:
NHL has always wanted to be in Seattle. However, nothing opened up with Hansen's SODO project. Then, as soon as Seattle City Council offered a positive response to a remodel of Key Arena....BOOM. NHL is going there. There was hardly ever a time when Seattle was a credible threat (although supposedly it was used that way at one point in the Phoenix saga).
It seems more to me like this:
Foley came to the league wanting a team. NHL suggested he work with Vegas. That worked out well. Foley has lots of $$, and could get in on arena ownership there as well. So, it was the perfect market for him, even though it's not a place we would have anticipated at all.
Seattle has been a market in target for a long time.
Now....
Houston also presents as a target market. Huge media market. Hockey history. I think the NHL actually WANTS to be there. The thing stopping them right now is that Fertitta, who controls Toyota Center, doesn't want to pay NHL prices, and isn't a huge hockey fan.
I don't think the NHL really wants to go to either Quebec or Southern Ontario. I think they want to be in the major US cities, and the reason is that they hope that being in the major US markets will get them a bigger TV contract. (Whether it actually will help that or not is another question)
So, in this case in particular, I don't think it's a matter of leverage at all.
Although, since many arenas will be reaching the end of their leases within the next 12 years or so, that's an interesting question: What happens when Honda Center in Anaheim has its lease run out? And, many other places.