The Martial Art's have certainly evolved more in the previous 50 years than ever before. What will change in the next 50 years?
What styles may disappear?
What styles will become or remain popular and why?
Will there be styles at all?
Will continued style consolidation much like MMA has done morph the meaning of martial art into something else?
I doubt that many styles may disappear. There may be a few fringe styles that do. I think it will have less to do with MMA and more to do with the Internet or changes in politics. For example, people are exposed to forums like this and may get more direction in what is a "good" vs. a "bad" art. Or, should North and South Korean relations improve, there may actually be a unification of KKW and ITF. (Or not, since they are different styles).
What we will see is people coming up with their own consolidated arts, for things outside of MMA. I take both Taekwondo and Hapkido. I can easily find ways for those to work together. Having watched videos of Boxing, Muay Thai, Wing Chun, Wrestling, and BJJ, I can see ways to apply all of those to what I know already. Now, some of those combinations are pretty popular already. Anything involving Boxing or Muay Thai with Wrestling or BJJ is a pretty good striking/grappling combination for MMA.
But I can easily see how learning Muay Thai or BJJ would combine well with my Hapkido. Hapkido tends to focus on wrists and elbows, and Muay Thai on shoulders. So that would help me work my way up the arm. Hapkido tends to want to stay standing, BJJ wants to go down. Wrestling would sort of combine the two - more focus on shoulders and hips, more focus on groundwork, and I could use my knowledge of submissions from Hapkido to apply it to the ground control of wrestling. So those provide a more comprehensive grappling style. I could combine Hapkido with Wing Chun, since they use a little bit different way of trapping and controlling your opponents hands and wrists.
Boxing simply fills a gap in my training, to get me used to sparring with punches and get me used to reading incoming combinations.
How many new combinations would come out of mixing Hapkido with any of these arts?