Sports cars are what the company was built on...it's rich history is all about sports cars and success in sports car racing. When Porsche was still independent, it added the Cayenne (with some platform sharing w/ VW) as a profit center (cynically cashing in on the overheated SUV/CUV market boom of the last decade).
Now that Porsche is fully part of the VW family, it really doesn't need the Cayenne or the Panamera, as those overlap with Audi models. But they are adding yet another SUV soon.
Consider Ferrari--they make sports and GT cars only, they don't do SUVs or luxury sedans. Jeep doesn't make sports cars or sedans. Porsche should be the same way, IMO...maintain the brand vision and focus.