I think it's an extremely interesting topic of conversation, and certainly one I've had several times. I believe that any one of the reasons you posted are possible, though in my own opinion this is the most likely specific reasons for the site "ceasing to exist":
* Some legal situation causing an injunction which ceases the site from being available - Your example used the Seahawks as the cause, but that's no really a concern anymore (for some of the reasons Les pointed out, but more notably that we're now looked upon favorably by the FO). A more likely scenario would be an entity suing the site for defamation of character, and an idiot judge doing something really, really stupid like approving an immediate injunction to cease and desist the site until the trial.
- Mitigation: Someone would simply purchase a new domain name and word would get around that ".net is now at newdomain.com until this gets sorted out". We've seen this exact thing happen twice, and it didn't end up killing the site, but it could.
* The site begins having major outage and performance issues, causing people to become frustrated and seek out other sites - One of the reasons we've been able to accommodate a readership that has grown exponentially over a 3 year period is by treating this "hobby" as a business and continually reacting to growing needs by building a bigger, stronger supporting host platform. But even with the donation/associate platform helping with costs, the numbers of users and views recently grew to a staggering number not even we could have anticipated.
As you all saw, the site's current platform simply couldn't accommodate that many users (during the Harvin & Avril news) and the platform is a top-notch Amazon web services system. 3+million page views a month isn't something we can accommodate using the standard shared server/storage/DB methodology, so decisions have to be made in order to build the new site out as a tier 1 website, rather than the current open-source platform. As was eluded to earlier, the large amounts of time and energy people are putting into site migrations, tweaks, rebuilds, and restores for no monetary compensation isn't sustainable at these levels. So as a business, either I need to adapt, or eventually the site will reach that scenario.
* A major change to the operating structure is implemented by ownership, causing community backlash that eventually leads to a mass migration to another board - This would be a major change to rules like "it's against policy to say anything bad about the team, the players, or AbsoluteNET and anyone doing so will be banned". Another version might be that we decide to start allowing advertising in every way, shape, and form and people have to put up with banner ads, pop-ups, and ads that say you cant view this topic until you watch an 8 minute infomercial about erectile dysfunction titled "What to do if you're a PEhawk".
These are the causes I see as the most likely, though you all should know I've always tried to do everything in my power to avoid these pitfalls. I'll always be loyal and committed to the site and the community so I have no intention of allowing those to happen, but business has to adapt and there will always be a chance that the decisions I make on how to adapt turn this place into the Seahawks version of Myspace.
Les - "Mark, you're my favorite player"
Mark - "Mine too!"