While BMW is collaborating with Toyota to build a Z4, Audi is collaborating with Porsche to build the R4. Which one do you think is going to be a better sports car??
Porsche nixed the R4 and the baby Porsche because they felt a baby Boxster is not essential for the brand deciding the Boxster is ideally the true entry Porsche.
But this is the limits for VAG they will not develop a single model unless there is a business case from the other VW marques making the project more cost effective. Porsche is if you use the term the stepchild to a disliked step parent. Which is why they have gone out of their way to prevent complete assimilation.
Audi are not happy about the R4 and will no doubt interpret R4 into the next TT.
But stories like this are common news known within the German car industry.