Square Enix has announced at PAX East 2018 that they're going to release a standalone version of Final Fantasy XV Multiplayer Expansion: Comrades for PlayStation 4, Xbox One and Windows PC during Summer 2018.
In addition, they revealed an update for Comrades will also be released in Summer 2018 and one in Winter 2018/19. The Summer update will likely add cross-play for the Xbox One and Windows versions.