While Sony has been letting a select group of beta testers try out near-stock Android 6.0 builds on the aging Xperia Z3 and Z3 Compact for a couple of months now, the newer Z5-series and Z4 should ultimately be given priority for actual official updates.
When will over-the-air rollouts begin? It’s hard to say precisely, with the Japanese device manufacturer staying as secretive as always, but based on recent Wi-Fi certifications for domestic versions of the Xperia Z5, Z5 Premium, and Z4, January seems like a safe bet.
The three phones have essentially received technical approval on all the main carriers they’re available on in the Land of the Rising Sun, and if Marshmallows are indeed slated to begin their local dispatch next month, international models (including the Z3+) shall follow shortly.
It remains unclear whether or not Sony intends to use the insight gained as part of the Concept program to minimize bloat in final M builds, but without a doubt, battery life enhancements are coming unmodified, alongside security tweaks, Google Now on Tap contextual search, total app permissions control, and knowing Sony, camera performance improvements.
Also, general system speed improvements. And plenty of fun new emoji if Sony manages to stabilize and optimize Android 6.0.1 in due time. Bottom line, the season to be jolly could run a little longer than usual.
Source: Xperia Blog