FF Versus XIII outfit designer lists game as “Final Fantasy 15"

[Soundwave]

I think it'll be a cross platform game, PS3/360/Wii U and PS4/720 as well.

Does "Versus XIII" really even tie into the story of FFXIII? If no, then renaming it FFXV makes much more sense. Why associate it with XIII when that's one of the least popular FF games for no reason?