Currently, there are two efforts underway within the IEEE 802.3 Working Group to standardize Ethernet technologies. The first project is the IEEE 802.3bp Reduced Twisted Pair Gigabit Ethernet project. The second effort was just started, and is referred to as Power over Data Line. So standardized Ethernet is coming to the vehicular market!
In my opinion , there is no need to phase out CAN in favor of Ethernet. CAN can and should exist and handle the control related electronics as an isolated network, whereas the Ethernet should handle all the add-on systems -built-in as well as user added .
From the Car's safety point of view such kind of isolation will keep the car systems safe from the hackers who could get entry through the Ethernet ports.
We will start seeing automotive Ethernet replacing CAN in eight to 10 years? I am not so optimistic. There is not yet an automotive Ethernet standardized, there is still considerable resistence against Ethernet from OEMs and suppliers, and it will take much time and cost much money to develop new ECUs with Ethernet support. But I am convinced, that sooner or later any kind of automotive Ethernet will replace CAN and the other buses of a car and will make the development costs in the end cheaper.