Today, Pixel phones and the top Samsung devices are guaranteed to get three years of major software upgrades. Working with Qualcomm, Google is now making it feasible for Android devices to get 4 OS versions and years of security updates.
In 2017, Google re-architected Android to be more modular, thus allowing updates to be easier and faster to implement. With Project Treble, OEMs can just update the OS framework without having to alter the vendor implementation (device-specific, low-level software).
While beneficial to device manufacturers, this approach “introduces additional complexity” for chipmakers:
For each SoC model, the SoC manufacturers now needed to create multiple combinations of vendor implementations to support OEMs who would use that chipset to launch new devices and deploy OS upgrades on previously launched devices.
The result is that three years beyond the launch of a chipset, the SoC vendor would have to support up to 6 combinations of OS framework software and vendor implementations.