I don’t think the NCAA has any legal rights in forcing schools and/or conferences to do something on an operations standpoint. From the NCAA's standpoint, the only legal thing they can do is control the post season as they do in every other sport in every other division which is utilizing a playoff. There is too much money at stake in the BCS games for major schools to risk losing their chance at a lucrative payout by scheduling other top schools. Sure they occasionally happen but definitely not at the frequency we fans would like to see.
My thing with including all FBS conferences a bid in a playoff is that more revenue would “trickle down” towards the non-BCS conferences and they would at least have a shot at a national championship (let’s not kid ourselves, even if Boise didn’t choke in Reno, we all know they had no shot at a BCS Championship bid). The NCAA is supposed to be for fair play and equality and all that other nonsense they have trampled on with the BCS and bowl system, a playoff system including every FBS conference would address this current shortfall. Also top schools would play other top schools in that if they didn’t win their conference, they would want a strong schedule in hopes of landing an at-large bid in a playoff. An FBS playoff system makes too much sense, so the NCAA will probably not pursue it as a viable option.