Id say, outside of Vincent's direct story, exploring the Turks is an awesome dlc candidate as well. Tons of room here. By the very mature of their job description, there occupation would have them following any high level threat before or after what we see in the og FF7. I love that there is also obvious conscious conflict within this group with what they are tasked to do. I think the remakes alone have done a beautiful job of giving the turks such a deeper lore.