Blizzard has previously stated that Diablo III will be available on current generation systems this year, but a next generation version will have to wait until 2014.
In an interview conducted by DiabloFans (via Polygon), the wait is due to the team only recently receiving PlayStation 4 dev kits and wanting to utilise extra functions like the share button and touchpad, instead of straight-up porting the Xbox 360 and PS3 version which will be released on September 4.
At PlayStation Meeting 2013, Blizzard took to the stage and revealed that Diablo III would be available on the then, just unveiled PlayStation 4.