Final Fantasy XIV's new expansion will be released this year, but we all don't know what the new expansion includes content. New areas? New jobs? New content styles? New mechanics? New races? New classes? Or something others?
The FFXIV game company is tight-lipped, so we don't know much more about the new expansion. Here are just some of the predictions and reverie.
New areas?

FFXIV has developed a system for gating flight, so i think we will get new areas in the new expansion. It seems likely these new areas will feature flight.

It’s not definite until it’s announced, but if without new places, the FFXIV's flight system may be added to the existing mount system. Both of them are surprised, if we have another mount that can fly from here on out, that's not so bad, right?
New areas or add the flight system to the existing mount system which one do you prefer?

New jobs?
The game company uses FFXI as a basis for future FFXIV development, in this case I think it’s appropriate. The FFXI game had one expansion without new jobs, and it received a lot of criticism for…I think we will get new jobs because they maybe learned the lesson.

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Here you may be to ask what about the new jobs for the base classes? I’m not happy about that, but the paradigm for further jobs has been established now, I don’t see us retreating from where we are now. Even though I like the idea of the whole class/job split, I really don’t think that we’re going to see more classes split off from the same base.

New content styles?

That’s just thus far, there are hints more is coming. The reason is Heavensward has introduced one really “new” style of content on the PvE side with exploratory voyages, a new PvP mode, and a new endgame setup for crafting and gathering, right?

So the new expansion may be reasonably assumed to add other elements into the gameplay on top of everything that’s already there.
New mechanics?

Merit Points, here we are! Players need more character customization options and those classes are kind of a relic. Heavensward built on the mechanics established with FFXIV. I think it will be in the next expansion.

This is just my conjecture, we haven’t heard much in the way of rumblings about it yet.

New races and New classes?
Unfortunately, until now, I don't find any hint of any new races and New classes will be added into the new expansion.
To be honest, I’d love to hear that both of them add to the new expansion.
What are you to believe? Or you can give me some better clues? All these are my personal speculation, the official website of specific information prevails.

Source: https://www.mmopixel.com/news/ffxiv-new-expansion-reverie.html