FFIX Missed opertunity...

[Enkidoh]

The thing is, I'm actually wishing SE had never implemented the FFXI and XIII events, as all it has done is then create this unrealistic expectation among the player community that SE will now automatically do an event for every game in the series just because they did ones for XI and XIII, which they never once stated they would. The FFXI and XIII events (and the Dragon Quest event too for that matter, but hardly anyone ever remembers that) were actually exceptions rather than the rule, and actually had a deeper meta connection to Naoki Yoshida in particular and FFXIV in general.

Specifically, the FFXIII event was actually born as the result of a private joke Yoshi-P shared with Lightning Returns's producer Motomu Toriyama, the later whom had miqo'te starting armour and the GC level 50 GLA/PLD weapons as gear in LR-FFXIII, and Yoshi joked that (paraphrased) "he would find some way to repay the compliment," by "finding a way to have Lightning appear in FFXIV." Of course officially it was also cross marketing for Lightning Returns's Japanese, US and European launches.

In a similar vein, the two FFXI events were officially to celebrate certain milestones in FFXI's long service, the first event was part of FFXI's eleventh anniversary of service (a similar event actually ran in FFXI involving FFXIV spriggans appearing in Vana'diel and running rampant), while the second event was to celebrate the final storyline mission expansion for FFXI called Rhapsodies of Vana'diel. Meta wise though, the FFXI events were also Yoshi's way of saluting Hiromichi Tanaka, the original producer for not just FFXI but FFXIV's original version (version 1.0) as well, the later which Yoshi succeeded Tanaka as producer and director of after 1.0's disastrous launch and development (which led to ARR). FFXIV was originally intended to be FFXI's spiritual successor (and the two games share a lot of concepts, player races, beasttribes, monsters etc), something it has now arguably attained, and thus the second FFXI event in particular referenced that. And the Dragon Quest event was to celebrate Dragon Quest X's first anniversary of service, the meta connection being Yoshi previously worked on DQX's development team before joining the FFXIV team, and it was a fond reference to his former project.

And even then, Yoshi already stated a long time ago that they will not be doing crossovers with FF games whose characters are either "deceased" or "games whose stories are complete". Accordingly it's possible we'll maybe see a FFXV crossover event in the future, and maybe a FFVII-themed one... but other games you probably have a better chance of seeing Nintendo sell Mario to Disney and go back to making playing cards than a <insert favourite FF game title here> crossover event in FFXIV. But then, stranger things have happened...