Most flagship smartphones that was launched last year, the Sony Xperia Z5 is one of them that is still running Lollipop. Rumor says that an update which is Android 6.0 Marshmallow is coming next month.
Twitter user Ricciolo said, Sony Xperia Z5 is scheduled to receive an Android 6.0 Marshmallow update next moth as in January 2016. He also said that other older Xperia models will receive an update after that, though no schedule of release has been mentioned. This is still a rumor until now though.
It will be exciting to see what kind of near stock Android they will have for Xperia users, since Sony has their own battery saving software, great batter lifespan and those devices are needed a push for an update.