It's not supposed to be coming anytime soon but here's what's rumored to be done:
>all new version of the game but with heavy asset re-use
>events from DLC and other media will be rearranged throughout the main campaign
>new playable areas
>no comrades stuff or online game associated things
>combat will be reworked to resemble 7R and more members will be added
Now that may strike people as odd, but with all the 7 Rebirth rumors it makes sense since it's supposed to have an open world to mirror the overworld in the original game where you ride around vehicles, so they're taking stuff from games they already are making
Source: Square rumored to be "revisiting" Final Fantasy 15 - Ganker
>all new version of the game but with heavy asset re-use
>events from DLC and other media will be rearranged throughout the main campaign
>new playable areas
>no comrades stuff or online game associated things
>combat will be reworked to resemble 7R and more members will be added
Now that may strike people as odd, but with all the 7 Rebirth rumors it makes sense since it's supposed to have an open world to mirror the overworld in the original game where you ride around vehicles, so they're taking stuff from games they already are making
Source: Square rumored to be "revisiting" Final Fantasy 15 - Ganker