Considering speculation so far, it will be based on XIV TRUST system as alot of Japanese FF players expected carry-over from XIV considering relatively fast XVI will be released.
Not to mention, by trailer launch, Japan PS blog kinda spoiled about Clive and party to be Sora-like party (player as Clive/Sora, the others are AI) and open world aspect will be limited to outside the town (inside the town will be traditional loading screen transition).
In recent Famitsu interview:
- At game start, you will given choice of "Story Mode" or "Action Mode". "Story Mode" is the Easy difficulty while "Action Mode" is Normal.
- Yoshida said its possible for players to just run straight to ending, this is because surveys he initiated during XVI shown games nowadays have low completion rate.
- FF XVI will have higher difficulty, score attack and challenge mode, and yes, Yoshida said it will be "restricted equipment, aggressive enemies" and "against group of enemies through levels" which means something akin to Dante Must Die and Bloody Palace for DMC.
- You can give party AI instruction
- XVI project is started roughly during Stormblood expansion of XIV.
- Yoshida expressed XVI to be a high-class high-speed roller coaster.
- Yoshida considered XVI as full action game.
https://www.famitsu.com/news/202206/22265843.html