There was a mixed OU/AU game a few years ago that had about a 50/50 split. It's hard to run an all-AU game because the playerbase is usually too small to be stable, but there are a lot of people who would probably take the AU option if there were enough OU players to keep the game afloat. Personally, I'm only interested in playing native AUs... there are still some of us out there haha.

Also, there's still a lot of Sky Tides nostalgia around here (defunct AU game with sky pirates from several years ago) so you could probably drum up some interest.