See, BFA's 8.3.5 will have to serve as an epilogue patch buliding up to 9.0 prepatch story but also end BFA, my theory is that one of the things they could have working on this is giving the undead/night elves and worgen a new home.
In order to create a home for them Gilneas could either serve as the binding agent that glues them together and thus we get the Lightforged Undead as part of a triad of 3 Gilneas themed cultures mixed into one, with Forsaken opting to remain with Orgrimmar for now.
It could lead to Gilneas City and the region being revamped to have a story theme around the restoration of the land itself, Tauren/Highmountain via Baine helping restore it from one spectrum while Calia discusses the future with Genn/Shandris from another.
This ultimatley leads to a compramise, a difficult one but by irony the very thing that once served to bring all 3 of these races into war, will now serve to be the thing that unites them.
The story potentially ending with Gilneas City being restored but now having a bigger asthetic and design with it having 3 themes, Lightforged Undead, Night Elf and Worgen.
Genn's people get the Greymane Court region but it becomes heavily more upgraded, the Military district becomes a new area for the night elves and the Blackwald gets a new mini world tree nearby, a world sapling that will grow over time.
And the Lightforged get the cathederal and all 3 share the merchant square.
Now alternatively if we had a Horde equivilent story:
Gadgetzan post hearthstone has become a rife land of criminal scum and villiany, revamped Tanaris gets made with Gadgetzan being the focus, the main story revolved around Gazlowe and Noggenfogger discussing the steamwheedle joining the Horde offically while the Forsaken proove useful in taking away Nogginfogger's rivals to power within it ultimatley securing themselves a district amoung the 3 major cartel rivals.
Forsaken and Goblins share the city together with criminal cartels now under the Horde's operation with the Steamwheedle finally breaking neutrality to declare itself a horde faction, save booty bay which refuses to take a side and continues to smuggle alliance to rachet.
Anyway that was a fun muse of sorts of my idea of what 8.3.5 could look like, with it being an opportunity to add lightforged as an allied race, for the horde, if gadgetzan -was a hub- one of the criminal cartels is very san'layn themed which might be a way to add them to the horde properly and not just a refference in a war campaign story for alliance.