Edit:
I don't believe there is likely even a difficult way to save Final Fantasy anymore, let alone an easy way.
I'm not sure if SE even did all of the following, that it could restore the Final Fantasy name for many long gone Final Fantasy fans..
-Perfect remake of FF Tactics that faithfully remains true to both the story and all the gameplay.
-Perfect FFXI 75 cap era Remaster that faithfully remains true to both the story and all the gameplay.
-Perfect remake of FFXI as it is now with all the content, that faithfully remains true to both the story and all the gameplay of the current version of the game.
-Perfect re-release of FFXIV 1.23b servers with a new story where the Warriors of Light save Eorzea and walk into Ishgard as heroes and champions instead of outcasts, that faithfully remains true to both the story and all the gameplay of the original 1.23b.
-Perfect re-release of FFVII-Remake that faithfully remains true to both the story and all the gameplay of the original game.
-Perfect remaster of Dissidia and 012 re-bundled and re-released that faithfully remains true to both the story and all the gameplay.
-Perfect redirection of FFXIV that makes all races have access to all hairstyles and equipment, a proper expansion that has actual new and exciting content, job adjustments that cater to both experts and new players (totally 100% possible), gameplay that also caters to both new players and experts (also 100% possible), a perfectly updated UI that has every single aspect of the UI with a toggle to turn off, and auto hide. Literally a full overhaul of the game, to make it enjoyable as a new player and an expert gamer, that is a proper MMORPG that is fun for everyone. (Also 100% possible, just takes knowhow.)
Even if Square-Enix does everything perfect from this moment onward, I do not believe we will see veterans return to the franchise.