We just have a report coming in, of an unknown Sony device, which got certified through the Federal Communications Commission in the United States, and since looking at the calendar, the device would probably be the Xperia Z4.
The information revealed is very little, and it only suggests that the device would be using the LTE 5 and 7 bands. Also a few days ago the device also got certified in Japan, and according to the reports, it would be featuring a Snapdragon 810 chipset, a display of about 5.2 inches with a display resolution of about 1440 x 2560 pixels.
Also a 20.7 MP camera, with optical stability, and as usual the Water Resistance. It would have a 3400 mAh battery to drive it power, and would be featuring Android 5.0 Lollipop on board. Yet there is no official word from Sony about the device, but we are expecting to hear from them in near future.