Unless people lose interest and let things lapse, I can't see why a site would go offline for an extended period. There have been a couple of times that we've been hacked - not the forums, but the website - and it usually took a day or so for me to get things back online. In the past couple of weeks, these forums have had a few problems - I have no idea if it was an 'attack' since I don't have good tools for doing that sort of analysis. I'm just glad that the SMF (forums) and mediawiki (website) software isn't riddle with security holes like some of the stuff I've used in the past (drupal).
Fingers crossed that it stays business as usual here.