You might know that Cyanogen, one of the popular custom ROMs ever created for the Android OS was renamed as LineageOS. After the LineageOS 15 and minor 15.1 update, it's now the time of LineageOS 16 release.
LineageOS 16 will be probably based on Android P(Android 9.0). This is based on the fact that Lineage OS 15 is based on Android 8.0 Oreo version. It could be the next LineageOS version.
LineageOS 16 Update
You got all the detail here:
The release of a new Lineage OS version is based on the official Android release. Every year Google releases a new version of Android and they name it alphabetically in order. Since last year it was Android 8.0 Oreo, this year it will be Android P, the Android 9.0 version by the Big G.
Tracking down the development in the Android 8.0 Oreo OS, currently, not more than 5% of Android devices run on it. So, the roll-out of LineageOS 15.1 is full-fledged. On the other side Android 9.0 P Developer Preview was out recently and there will be second preview version to be available next month.
LineageOS 16 Release Date:
The Android P could hit the AOSP in the month of September 2018 and the first Lineage OS 16 build could arrive as early as November 2018. That's really a long wait and the reason to blame for it is the Android P AOSP build release. The stable version might be released by the end of the year.
Now coming to the list of devices, there dozens of smartphones and tablets that are expected to get it. Highly customized Android version smartphones from the brands like Xiaomi, Samsung, HTC, and Sony haven't received much love to Lineage OS over the past few years but Pixel, Nexus, Android One Phones and HMD Global made Nokia devices are the prime contenders.
LineageOS 16: List of Eligible Phones
Download links to all the compatible phones coming up soon!
As of now, nothing is official and this is completely based on assumption and past history.