And so Lightning Returns.... (Again)!

[Nestama]

It kind of defeats the purpose of a special event when you keep bringing it back.

And from a lore perspective... it kinda doesn't make sense for Lightning to 'return'. Shantotto and DQX are more than welcome to return though, since Shantotto can traverse dimensions (A Shantotto Ascension) and DQX used mostly FFXIV races.