Nomura-san remarked it's a "delicate situation within" Square right now, and that the "details as to why" they couldn't name the date might also be revealed during the next announcement.
That 'delicate situation' refers to the rather disappointing end of fiscal report for the publisher and subsequent resignation of current CEO Yoichi Wada.
"It's a delicate situation within the company," explained the game's director. "The date for our next reveal is set and we are working toward preparing information for that. Perhaps the details as to why information couldn't be released might be touched upon with the next information announcement."
Rumours are circulating that Versus XIII has become 'Final Fantasy XV' and will be for PS4. Will it at E3?