This actually already happened, to the extent that it ever made a difference in the PC ecosystem. The manufacturers of cheap phones in China use standardised mo

This actually already happened, to the extent that it ever made a difference in the PC ecosystem. The manufacturers of cheap phones in China use standardised modules: motherboard PCB, display with standardised connector, battery, "open mold" (a standard mold designed by a design contractor for the chipset vendor, open to many manufacturers). This allows them to quickly assemble low-cost phones with components from a large number of manufacturers, driving down costs. So the financial benefit that came from the open PC ecosystem has already been realised on cheap Android phones, the equivalent of the crappy PCs assembled from lowest bidder components of yesterday (Dell, Packard Bell, etc).