I would not mind having Blitzball, would be indeed interesting beside PvE and PvP, to have an actual "Sport Event". But there is the thing, you know.. SE have to create TONS of Animations, not only for the Characters, but also for the Actions.. let alone it being under water and for a 2014 Game it should be 3 dimensional. Alone the Animations for that, not counting in the Game-Mechanics itself, the Rules, the Environment etc would cost probably as much as an expansion.

So do i would like Blitzball? Yeah sure, but not going to happen unless SE is going to make an Expansion out of it.