Android updates are rolled out by phone manufacturers and network operators rather than Google itself, because any Android updates must first be tweaked to work with any customisations they have made. A consumer preview of Android 9.0 will most likely be announced during Google I/O 2018, which we expect to take place in mid-May, potentially 16-18 May 2018. As before with Oreo the developer preview was announced earlier in March.
A few public betas will follow, and we expect to see the final consumer release in August 2018.
According to Android Developers, key new features in Android P include:
Simplicity, speed, and many new ways to extend your apps
MessagingStyle and other notification updates
ImageDecoder for bitmaps and drawables
Data cost sensitivity in JobScheduler
Display cutout APIs
Things we would like to see in the new OS include a faster rollout and less defragmentation among devices, improved Picture-in-Picture app support, and further enhancements on battery life and performance.
Google is also working on another operating system called Fuchsia, which some are saying could replace Android in the longer term.