Hn.  In my mind, the immediate answer is "force it."  Do a write-up of a Nexus of Worlds setting that ends up stickied here in the Arena, and as part of that setting, cross-link from the write-up posts to persistent threads in Advanced Play where people can go to do the badass-bar thing.  Or the castle thing.  Or whatever else they end up doing.  I imagine players who wanted to could use events in the Arena to set up less-combative (situationally) threads in Advanced between their characters.  I'll admit, the Guild's overall structuring is...not terribly conducive to any sort of persistent-world game (which is quite probably the biggest reason I'm mostly just faffing around in the Arena whilst I'm here) - but that mostly just means you need more elbow grease in keeping track of it.

I've seen people do it with less.  I've also seen people do it in the face of hostile administration, at least for a little while.  Mostly just have to pull together and get everyone pointed in the right direction long enough to pick up some momentum...which is, admittedly, one hell of a trick.  Perhaps your Gaian Combat League could be a start point.  I dunno.  what I [i]do[/i] know is that everyone here seems to've seen/been to places where it worked, so the experience is there.  Just need to translate it into action somewhere, somehow.