I think long term yocto and build root are going to be replaced by container tooling. Theres not that big of a difference between compiling an OS image and building a container image.
Well one difference is that docker lives well above the metal and in a nice cozy environment on mostly standard operating systems and yocto builds that nice cozy environment for all kinds of nonstandard hardware.
Yeah agreed they are targeting different environments, but at the end of the day it's tools for building root file systems. I expect that to converge to better tooling.