The announcement is yet another sign of the way the Mac is becoming a sideshow for Apple. While the company has a senior vice president of iOS software, there is no equivalent position on the Mac side.
It's not that Mr Riccio doesn't have any Mac background: the joined Apple in 1998 as vice president of hardware design and according to a company statement he "has been a key contributor to most of Apple's hardware over his career."
Mr Mansfield's retirement date has not been announced. He will remain in charge of the hardware engineering team until the transition is complete, a process that is expected to take several months.