Like I said, that's the only reason the FFXIII event was held - it's to advertise the launch of Lightning Returns which is released in the US and Europe next week - it had nothing to do with fanservice. Otherwise there's little financial incentive to bother with the expense in labour costs to model such outfits into the game. Besides, I think players are getting sick of crossover events and just want FFXIV to stand on it's own merits. A little fanservice here and there is fine, but you have to draw the line somewhere.

Also considering it was asked here a while ago whether SE would be adding a simillar FFX/X-2 crossover event to ARR to coincide with the FFX/X-2 PS4 rerelease, and SE actually categorically stated 'no'. So it makes a FFVIII event seem even more likely.