i like to see that. if they manage to do it right, FF would tremendously benefit from it. but better not risked it if they aware they cant pull it of or it would be end up like FFXV.
just multiple big open area where player can roam from location to location is enough. each area is big enough to the point player can ride flying mount like Chocobo and even dive underwater. Witcher 3 and Monster Hunter World also utilize this multiple big open world area. the world structure and quest based progression also similliar to game like Xenoblade Chronicles where it is linear progression in big open area, travel foward from other region to another region which is similliar to older 2D FF is. over half of Heavensward basically linear in simillar fashion. they no need to look far. just look at FFXIV. put away the online element, it is not much different from single player RPG like Xenoblade or even Skyrim.
when i know CBU3 gonna develop FFXVI i excited due to this. im expected even if it not open world, but tons of big open area connected where player can roam, full of monster and there is big cities available but however, what we get with FFXVI is opposite of that. totally not what i expected at first place. what they carried from FFXIV is only the quest based progression and side quest system THATS ALL. there rest, they chose to take from Sony's linear cinematic approach instead. not say it is bad, it has it charm and i can see why they did this but the cons devalue lot of aspect for ambitious RPG on big worldwide continent like FFXVI. FFVII Remake is fine since Midgar just small location.
not just that, its like the devs copied MGSV's motherbase system where Hideway end up as main hub. so instead of the progression is about roam journey from another location and discover another location directly, it end up become majority strictly centered one click pray return to mainhub>fast travel location>fast travel main hub instead. this is similliar issue that held back MGSV here the big world end up feels narrow, just like quick fetch mission location. there is no urge or need to explore by ourself at first place. it is all about quick arrive and return back and the location also feels boring perhaps due to it is designed with this purpose in mind from very beginning. FFXIV also has Rising Stone or House of Fortemps but it didnt handled that aggresively. the two location existed and reachable within one big area however the Hideway and the motherbase is disconnected from the world in closed space instead.
no need to go open world. the structure they choose with FFXVI might be right all along but the MGSV-esque motherbase structure with Hideway>location>Hideway instead of world map exploration location>location>location ruined everything.