I wonder if the issue with delay of the new Audi 4.0 litre V8 is related to how to integrate it into Porsche's line-up?

It could end up in the Panamera, Cayenne, and GT V8; Audi S6, Q7, S7, A8, S8 and R8; Bentley Continental GT and Flying Spur. Personally, I believe Porsche should develop its own flat-8 engine, if a fast and frugal version of such an engine can be produced.

I don't think the Gallardo will use a V10 again nor a V8. instead, i think it will get a detuned version of the Aventador's V12. That's what I'd use to maximise ROI on that engine. it won't hurt the Aventador because only 4,000 units will be produced in total under current production plans.