Several screenshots allegedly taken on an Xperia Z4 Dual give us a peek at the new UI coming from Sony and confirm that the flagship will have a dual-SIM version. One screenshot shows a Qualcomm MSM8994 chipset, aka Snapdragon 810, and Android 5.0.2.
The interface sticks very close to Material Design though Sony still made some modifications.
The Sony Xperia Z4 and Z4 dual are supposed to have a 5.2" 1080p or QHD screen, Snapdragon 810 chipset with 3GB of RAM, 21MP camera, waterproof body and stereo speakers. With such a concentration of leaks, we would be very surprised not to see the Xperia Z4 at the MWC in Barcelona (the Xperia Z4 Compact, Z4 Ultra and Z4 Tablet should also be unveiled sooner or later).