Docker is drifting towards being a standardizes deployment unit. This is especially apparent with advent of Alpine Linux based images or even more so with distroless.

With these changes going on, docker becomes just a fancy zip file, and since now there is a committee to design a standardized container there really is nothing left for for the Docker company.

Kubernetes IMO just used Docker's popularity to gain its own, but at this point the actual docker itself is no longer essential.