Same genres as now. Don't see it changing for a while. I also see fighting games getting a lot bigger, especially with the release of SF5 soon, and the competitive scene of smash getting a lot more exposure in the last few years. There is possibly room for an arena type shooter to enter mainstream competitive, but likely not since it's extremely hard for casual players to get into since those kind of games are extremely technical. Games like CS and League have a lot of depth, but are also extremely easy to learn and play casually which helps develop a fan base for the competitive scene.