Project Treble is an effort to separate driver and Linux kernel. And later Android added mechanism to upgrade kernel from play service. I guess Google is resourceful enough to hedging on different approach to solve a similar problem.

However, the crux of the problem is the Android manufacturer. You can't solve a human and incentive problem with a technical solution. Project Treble makes manufacturer easier to support their device, but they still don't motivate to do it. Google needs a tighter control on what device manufacturer should release.

Android One is a good approach, only qualify certain devices to be include for meeting certain criteria. They could actually create a watermark on unsecured device for not updating Android version, just like chromium do it to website not using https. I think this is more effective than creating a new OS just to let the manufacturer being lazy.