Not official: This page is created based on leaked or rumored information. However, it seems it will never be officialy announced.
Hardware & Performance
The Sony Xperia Z4 Ultra, it is said to feature a 6.44" Triluminos display, the same Snapdragon 810 chipset with 4 GB of RAM as the Z4, but a lower-resolution, 16 MP camera with dual LED flash. Its other selling point will be an extremely thin chassis, to the tune of the amazing 5.7mm. Knowing Sony, and the fact that the original Z Ultra was long the thinnest smartphone on the market, we are inclined to believe that number.