the 'bigger and more of' approach to current systems (ie. more travel, bigger rotors) is too obvious and not likely, since certain requirements have already plateau'd anyways. For example, we already have had bigger travel bikes but its been found that not only its not needed, but can also be detremental and present too much comprimise as far as design (like high BB's, large variations in geometry...). Also stuff like massive or dual rotors may add unecessary weight and fragility, where superior friction compounds or better cooling through material and part design (like the Hope Ti6s) can produce more than adequate braking power that people can use (hey, some people will never go any faster then they are capable of anyways).
Going from the trends in DH/freeride tech, i think it can be summed up as a complete divergence from road bike technology, where everything came from. So far we have larger headsets, suspension, hydraulic disk brakes, 2 piece cranksets (which may see larger BB shells one day), larger front and rear axles, derailller and gear arrangment variations.
One big evolutionnary step i expect is to lose the derailler for some kind of internal gearbox. The rest i see is mostly refinements in current technology, from suspension (air springs, better tuning, lighter weights), better tire compounds and more UST support, more component and frame refinements. I wouldnt expect huge drops in weight since that is a materials limitation, but manufacturers gain more experience all the time to use it slightly better the next time around. I think most improvements at this point will be incremental and not obvious, mainly an increase in quality and value.