XV-2 isn't happening anymore. Nomura's multi-game dream is dead. The new CEO wants to move on quickly from now on after the mistakes of letting the XIII series linger.
Eh. I'd gladly take some other mistakes like that if I can play games that I enjoy as much as XIII-2 or even Lightning Returns. Difficulty aside, FFXIII-2's battle system was an improvement over the first and LR has, for me, the best implementation of ATB in FF yet.
Even not knowing how good FFXV will be and even if it doesn't need a sequel (XIII didn't need one, they expanded the story), how can we say they can't make FFXV-2 and that it wouldn't a better game? Some universes are too good to be used only in one game.