For the most part, each major patch brings a new landmass or area with some new stuff to do there.
So far we know the 6 original zones for BfA. Where do you think the next couple places will be?
Another island added offshore, or maybe underwater?
Something completely out of the way, like Argus? Maybe K'aresh?
Some place in one of the 6 zones they never finish on time and then add in on a patch?
Something completely redone in the old world?
I could see any of them happening with how generic it is starting off.
To add, we know Azshara is coming, so that gives some clues.