Bentley may opt of sharing Porsche's chassis architecture altogether but Porsche is aiming for an aluminum base for the MSB and considering how heavy Bentley models are it may be a no-brainer decision. Regardless, Porsche is determined to maintain their own brand character and that is a good thing.
It will be interesting to see how the next generation motors differ. Expect them to be around for a while according to Porsche chief engineer Wolfgang Hatz, “Porsche will have its own new V8 that will be common to the new MSB platform. It’s a family for the next 10 years of cars.”