Leica issued a 28/1.7 FF fixed lens camera, Leica Q, and it is sold before it hits the shelves.
Amazing camera, you really need to try it. Seeing is believing.
So there is market for such things, but it must be premium photographic stuff. APS-C isn't best thing for that anymore: Ricoh can't sell GRII for $750, even if they want, but Leica can't make enough of Leica Q cameras sold at $4250.
But the FF sensor, great features, great build quality, and a gorgeous, bright, versatile lens is the key. Leica has a fantastic nose for those things, and can surprise people.