Pretty much every FF release since XIV was an action game. We had FFXV, FF7R, Stranger of Paradise and FFXVI (I guess the only exception is FF7 Ever Crisis, the mobile game). It's clear that they want to keep pushing the genre as it has been very successfull, and also knowing that FFXIV is doing pretty well on his own, I don't think they wanna get rid of it so soon nor release an MMO too similar to it. Which is why I think their next MMO will be an action game instead of a tab-target one. Now, knowing how much they evolved in their action games I'm not too concerned about it, but what to change and what to keep from FFXIV? Here's my own perspective on this:

What to keep

- All jobs in one character
This is the best thing about FFXIV and one of the main reasons why I don't play other MMOs. It makes the game a little alt-unfriendly sure, but who cares? Having all jobs in one character is awesome.

- Focus on the social aspect
That's another think about the game that makes me hard to leave. It's what makes FFXIV feel so alive. We have crowded cities, bards, venues, glamours, fashion accessories, adventurer plates. I just wish we have more accessbility options. We wouldn't be able to do what we do with bards/venues without third party tools.

- Level-based skills
Maybe skill trees are alright as long as your "skill currency" is gained by level and you have them all at max level. I just dislike the idea of unlocking skills via quests or shop. Imo the worst part of FFXIV's leveing experience is when I have to quit a dungeon queue and disband a party to enter a solo instance.

- Fast Travel
That's obligatory in every MMO. If you don't think so go play New World.

What to change

- MSQ is optional, content is unlocked through leveling
We all love the MSQ, but why does every single thing in the game need to be attached to the story? Why can't I do Island Sanctuary and Criterion Dungeons before Endwalker? What about raids, exploratory zones, flight, mounts? That's what makes the game so alt-unfriendly.

- Holy Trinity
I don't think Holy Trinity works really well with action games. Since most of the mechanics will be around dodging, timing and positioning, we won't need a tank and a healer every single game. It also makes queues really long.

- No Beginner/Secondary Classes
Yeah I want to play Black Mage right away, I don't want to level a Thaumaturge first. Why the hell is called Thaumaturge anyway? Thaumaturge means saint.

- Auto-loot
You know what auto-loot does? Fills your inventory with crap. You should be able to pick whatever you want from the enemy drops.

- Loading Screens
Yeah that's not going away. Every FF has a shitton of loading screen, except for maybe FFXV.

Well, that's all just basic stuff. I probably forgot many things. What about you? If square released a new MMO, what would you like it to have?