Thinking about this more... While I'd definitely get this for the world, I think a Fashion Designer career where you actually get to make fashions is probably a bit beyond even an expansion pack if they want to do it right. It would require dozens of locked clothing items in multiple colors (though it would be a time to introduce sliders for clothing) to the point where there would be almost nothing in terms of CAS otherwise.
Because to do a Fashion Designer right, you'd need to be able to frankenmesh on the fly (and even that's not quite right), and the game simply isn't capable of that. So they'd instead have to have a limited list of sleeve, bodice, and skirt options, and then every possible mesh combination already in the pack. And that's a number that will get very large very fast. Even if they were to separate out tops and bottoms and not actually have any full-body outfits (just tops and bottoms that looked like it.
So probably not practical.
Now, none of this affects a model career, but as I've already said, that's not something that interests me. However, as long as the world looks cool, and it includes other Gameplay options (which it probably would) I'd probably still find the pack fun.
