The idea of having more then one-on-one is rediculous and we all know that.
The idea of having it relay style say teams of 3. Having a sucession of one-on-one fights were the winner stays out with a short rest (a little longer then the one between rounds) until one team is complete eliminated would be very cool, however I doubt it will happen.
They could take an idea from Judo, at some Judo tournaments I've been to they have had team fights. Teams of 5, but it's just 5 one-on-one fights and now that I think of it PRIDE has done that with the bushido team main events for quite some time now.