There are two things I can see becoming big this generation: emphasis on a split between competitive arena gameplay and casual large-scale gameplay, first off. It could basically become the ranked / social split of the generation where level-based unlocks, larger more baroque sandboxes, vehicle combat, etc. dominate large-scale gameplay, and then on the flipside "arena mode" is more of an intimate, one-on-one and teamplay-fueled experience with smaller player counts. Second, the notion of fine-tuning concepts into more minimal functional suites, but with the ability to customize them substantially in alternative modes: SSB4's already sort of doing this with character customization, for example.