We're Seattle -- we have options. We could pursue the Golden Baseball League model and form an independent basketball league, or, better yet, a league of smaller basketball teams. There are other sports to consider, like, say, hockey. It doesn't have to be a National Hockey League team -- how about supporting the existing Western Hockey League? If this is about keeping arena seats filled and giving people who love sports something to enjoy, then we could do worse.
The problem with the hockey thing, especially the WHL Thunderbirds, is that they're already leaving Seattle. Not to say we couldn't draw another minor league hockey team to Key Arena and have a great local derby between Everett/Seattle/Kent, but that's going off in another direction.
I love this idea of a competing winter basketball league. Unlike baseball, and to some extent hockey, there is no organization top-to-bottom in basketball. All of the independent basketball leagues in the United States operate independently from the NBA.
List of minor league basketball leagues
Since the ABA merged with the NBA in the 70s, there has been little competition with top flight basketball in the United States. Taking the opportunity now to compete, I could see putting into play a handful of things that would strike at the heart of sports over here.
A new basketball league (or rather system) could involved promotion/relegation where good teams go up and bad teams down. In this way, you could invite teams from existing leagues to compete.
Community ownership could also play a role. The NHL supposedly played with this idea a few years ago, but outside of the Green Bay Packers and some other minor league teams, it is untried. Ask any fan if they'd buy stock in their team though.
Also, is it totally necessary to have a t.v. contract? This doomed the ABA... so, for now, despite internet and all that, I guess it does.