Human
You. The Road. Nothing else.
For now yes. Especially because of their substantial ~50% of the VW Group. In the long run Porsche will likely need to develop customize Audi and VW engines for their own use to maintain a distinct advantage over Audi cars. The last thing one would want is the Macan not being any different from a Audi Q5-S. However VAG is currently managed by the smartest men in the automotive industry and their product planning is second to none. So I doubt they'll fumble over their own egos like GM and produce line-up of cars that make no sense what so ever.
I agree and VAG's board will play this out on a fine line, Piech his Viceroy and his soldiers know better than anyone else how 'holy' the Porsche brand is and how important it is to them. And as Deckhood mentioned: "the brand which return the most profit per development."
