Google has been letting developers test and get used to Android 6.0 Marshmallow, the next release of its mobile operating system. The Developer Preview of Android Marshmallow is available now to owners of Nexus phones, with the final version launching on the new Nexus 5 and new Nexus 6 within the next few weeks.
October 5th is when the final Marshmallow code will be pushed to AOSP too. These are going to be the LG Nexus 5, Motorola Nexus 6, Asus Nexus 7 (2013), HTC Nexus 9, and Asus Nexus Player. That means the older LG Nexus 4, Asus Nexus 7 (2012), and Samsung Nexus 10 will not be receiving any more official Android updates from Google from this point on.