Will weight training be used less as time goes on?
I'd say yes. Weight training in the MMA context (along with plyometrics and various other non-stamina training aids) takes time away from skill development. Normally, this would not be much of a problem--in most combat sports, your technique can only get refined up to a point. In MMA, though, there are so many dimensions that well-roundedness, a plethora of different skills, and experience are paramount. Every second would have to be devoted to learning and practicing those skills. Fedor is an excellent example, though he still does chinups and pounds the occasional tire.