I've had similar thoughts. I talked to some gym owners and they suggested something different. They suggested buy the building and having lots of different disciplines rent particular rooms and times to do their respective classes. For example one of the guys I spoke to had large building. He had a weight room and cardio area along with an open area for boxing with a ring and the assorted bags. Along with all of this he had 4 other smaller studio type rooms that other teachers used to train in. He had a judo/bjj/freestyle wrestling and the assorted TKD/karate etc. Basically he charged the classes by the hour or they could setup a longterm lease. He seemed to like this best. That way he wasn't having to worry about ways to fill each particular discipline. The hard part obviously is convincing someone to move their classes into your building.