Hm.. I don't know. If the game would be called "PlaneShift offline" or whatever it wouldn't be an offshot or splicing or however it's called.
I think what will be supported and what not strongly depends on the story you like to have in this game.
If you have a storyline that plays before (settings-technically in the past) of what is happening now or in some shadow/parallel universe or whatever to prevent that people will mix up the storyline offline and what is happening now ingame, I think it could be acceptable to help out with PS art like maps and meshes, textures.
Afterall it willl require you to work under the Atomic Blue NPO and you'd have to accept Talad, Vengeance and Acraig as the official bosses.
I for one find this idea pretty good and I can imagine that it could draw more interested devs to PS in general when they see the offline version.
Done correctly this could boost PS (the MMORPG) development in general. I vote that you contact Talad on IRC or send him an email with an outline of your storyline.
You wouldn't require access to the online database and everything else you need is there.. I'd say go ahead and propose your idea
Good luck.
