Lore wise,
Black Marsh is very likely to be the next setting for the Elder Scrolls. It all makes sense.
The Thalmor are slowly conquering all of Tamriel, and Argonia would be pretty much the only province capable of defending themselves agaisnt the Thalmor. They're on par with them.
The elves would probably leave it for last, so there'd be a lotta refugees from other races in there,allowing plenty of room for non-Argonian player characters and NPCs.
Both Alinor [land of the Thalmor] and Argonia were the only provinces capable of scaring the daedra off their lands long before Martin Septim even had a chance to end the Oblivion Crisis.
Besides, Argonia has a long history of being unconquerable. It was the only province the mighty Tiber Septim himself failed to conquer after countless failed attempts, and he was only able to get them to join the Empire through an agreement.
Plus, it would have the same alien-ish feel of Morrowind.
I'm surprised no one commented on this.
It actually makes a lot of sense.
Y'all are just a bunch of Stormcloaks hating on the beast folk. lol.