OnePlus held an AMA about its newest device, the OnePlus 5T. One of the inquiries referred to Googles Project Treble. For those who havent heard about Project Treble it was announced several months ago as a feature of Android Oreo. In fact, all phones that shipped with Android Oreo out of the box will support this feature.
Project Treble modularizes the Android Operating system so that OEM customizations stay separate from Android. The idea is that OEMs dont need to tweak the update as much to cut down on time between releasing updates.
So back to OnePlus, in the AMA a fan asked if the OnePlus 5T or any other OnePlus devices will be updated to support Treble indirectly asking if any OnePlus devices will be fast-tracked for updates. OnePlus confirmed that neither the OnePlus 5T, nor any other OnePlus device, will be updated to support Treble.
OEMs can update devices with Nougat 7.1 and older to support Project Treble, though this does require reworking of OEMs firmware so many of them may not bother with Treble until a future release.
Source | More about Project Treble