http://gamrconnect.vgchartz.com/thread.php?id=215920&page=1
Four months ago AMD confirmed that one semi- custom will launch this year and two next year. The Xbox One S I using a semi- custom it enable 4k videos and HDR. So the PS4k will also need a semi- custom to work with 4k video so we can assume its the second one. Also, the PS4 already uses an AMD chip so it makes sense for Sony to continue to work with AMD. Then there's Microsoft. If they are trying to have an Xbox ecosystem of platforms they should use an AMD semi-custom. That would make the one release this year and two releases next year.
If this is true then we can assume Nintendo has made a partnership with another company and they are not using the same type of architecture as the other consoles.
