unpopular opinion for sure, but, given how FFXIV is story-driven, i do not really want a long term story beyond the Hydalyn/Zodiark arc as it stands already. Murmurs say we are 80ish% through the story or on pace to be following the conclusion of 5.0. That means potentially 6.x and 7.x would be more or less the end of the game. That being said anyways, I wouldn't want another decade of XIV that ends up giving less by trying to give more (what I mean is by muddling the lore, or stretching ideas to satisfy the demand that may or may not be there at the time of potential release and souring its audience similar to how long franchises/series/mmos tend to do).
We are told frequently that there is great difficulty in adding x y and z whenever the requests become particularly pressing. Further, people frequently complain about lack of content in the end game (and when there was, everyone complained about it in the form that existed as diadem and Eurika. And oh man, now everyone complains that they can't do Eurika, crazy, but then again, no surprise all the same. I'm sure that this complaint will follow whatever will replace Eurika as well).
I'd rather XIV end in good tidings and memory than dwindle and fade slowly like a flag left to the elements.
As far as the next FF mmo? I wouldn't know. I very much like FFXIV, and don't necessarily want something new then what I already have now, but if I were to guesstimate, it would be released 5-7 years after the final story chapter of XIV
