Don,

Why would you expect manufacturers to share RF/TTL flash capabilities when they have not in the last 50 years decided to share a lens mount and interface? Once they started to get into auto-whatever the ability to use lenses from one manufacturer on another brand camera rapidly disappeared. It would certainly seem to me that there is more of a potential sale upside to shared lens platforms since most people spend a lot more on glass than bodies. Well, that was more true in film days when the sensor (film) was upgradeable without buying a new body.