Audi A5 sportback?

Many seem to think Audi is working on a 4 door version of the A5. With either a hatchback or even a sort of low wagon type rear end. Like the new Scirocco.
Why not?
It doesn’t make any sense to me when they already have the A4 that looks almost the same as the A5.
Why not make a hatch version of the A4?