Ah, but are those going to be different brands across companies? After all, most auto manufacturers have multiple brands (traditionally, the big three automakers had a low-end, middle-tier and high-end brand, e.g., Ford’s Mercury-Ford-Lincoln trinity, although in the last thirty years a number of brands were shuttered. Add in international consolidation (Chrysler was owned for a while by Daimler-Benz and now by Fiat, Ford used to have an ownership stakes in Jaguar, Volvo and Mazda among others) and you might be seeing intra-corporate part sharing, not inter-corporate.
It does happen that smaller car makers will use parts from other makers in their cars because it is too expensive to design and produce all of the parts themselves. Switches, tail lights, etc are often done this way.
It is not uncommon for parts that are made by third parties will be used in cars by different makers. Aisin makes transmissions used in many brands. This can backfire when the third party maker has a production problem which affects a wide range of cars in multiple makers. The Takata air bags were used in many brands of cars until they were found to blast shrapnel into the faces of occupants. Takata has been struggling for years to produce enough replacement parts to fulfill all of the recalls.
