Morrowind is unlikely to change THAT much, unless it does a Cyrodiil and rapidly changes it's environment completely. It'll still be the same old mushroom trees and ash. As far as I'm aware, Argonia doesn't technically encompass Morrowind and I doubt they would make it so that it would as it's already a complex enough place without adding a whole extra province for a game. Daggerfall I don't really even count, since it was such low graphics that it could have been just about anywhere. It would seem totally different. Also, it was a much smaller area than Vvardenfell, which takes up probably about half the landmass. I find it unlikely they would do it when there are so many more regions.
So you think that the Argonians invaded Morrowind then just left? How does that make any sense? In the more than 160 years since the Infernal City (and who knows how long since the Red Year), they'll have had plenty of time to build new Argonian cities in mainland Morrowind. Bethesda isn't going to not give Morrowind to them just because they don't want to be bothered making more content when they finally have to make a game in Argonia.
And yes, Morrowind has changed THAT much, despite you trying in another post to make it seem like it was this tiny little event. The biggest volcano on Tamriel erupted, Vvardenfell is now circle-shaped and covered in ash, the sea around it is still boiling, and there's a bunch of Argonians where the Dunmer once were. I don't care how much you dislike the thought of seeing more of Morrowind, you can't deny that all of that is a
big change.