The future I see is kinda painful but necessary or inevitable to get to the next esports level.
A mix of Tekken Revolution (rpg elements), SFxT gems, LoL/KI rotating DLCs, and other F2P and P2W shenanigans.
You start with just normals then pay to unlock special moves, then pay to unlock EX versions that you can level up, then unlock Super/Ultra/Ism/X-factor. I see fighting games with more melee weapons that you can customize, some have guard break ability, others can be charged to be unblockable, some are able to parry etc.
A ton of customization options like in SC5 and Tekken. They won't sell DLC costumes they will sell individual parts and accessories like in KI. You'll buy taunts, winning animations, character portraits. etc.
I also believe the fighting games of the future won't be fighting games only. I envision a Mortal Kombat MMO (either F2P or 15$ a month) that would play like Konquest Mode+Shaolin Monks but in a really huge and rich world. Of course it would (or should) still be a fighting game at the core but with all the social interactions of an MMO adventure RPG.