Sony is expected t be working on the Xperia Z4 Tablet Ultra, which has a display of about 13 inches. Sony is expected to release the next generation of it’s smartphones, i.e., the Z4 series, and the 13 inch tablet will be a part of it.
The name would most probably be Xperia Z4 Tablet Ultra, it would feature a Triluminos IPS with X-Reality with a display resolution of about 3,840 x 2,400 pixels, which is 16:10 4K UHD. it would be powered by a Snapdragon 810 with processor clocked at about 2.86GHz. it would have 6 GB of RAM, and about 64 GB of internal Storage. And also the device would be having the PS4 Remote Play Support, which is quite expected.
It would feature a 1/2.3″ Exmor RS sensor along with f/1.8 Carl Zeiss Sonnar T* lens and an 8 Megapixel sensor. The tablet would be quite thin at about 8.6mm. But that big device, with such slim body would be difficult to hold on to. Most probably it would be going live on the CES or MWC in the coming year, i.e., 2015.