Sony has reportedly started R&D on the successor to the PlayStation 4, according to a recent job listing posted by the hardware giant.
The job ad, which calls for a Senior Game Programmer, describes that Sony is looking for an individual 'to assist [them] in developing a game used for R&D purposes related to [them] next generation gaming system.’
http://www.psu.com/news/26860/Sony-has-already-started-R+D-on-the-PS5
As expected.