I think the level of fighter will grow by leaps and bounds. ...what I mean is, most fighters today have a "style" or a discipline they point to as their strength (ie Wrestling, MT, JJ, Boxing, etc..) and play to that strength...but have (by necessity) started to learn (and some very well) other disciplines to remain competitive. But they are still lacking in one aspect of the game for the most part in comparrision to their core art or discipline. Today, those that are most successful have brought their weak points up to their strengths.
Right now...kids that are training (and will be competeing in 20 years)....are the first generation of TRUE MMA fighters...trained (from a very early age) with the mind set to be good and excel in all disciplines, not play catch up on one or the other. I dont think you will see (as much as you do now) Fighter A is a jj guy who has been working on his Boxing so he needs to get it to the ground...or fighter B is a striker but has no ground game so he needs to keep this one on the feet. I think that in 20 years the kids of today will be outstanding at every aspect of the fight and the sport will explode with world class talent