This has been something that's exploding all over the internet. I'm primarily on Twitter from a social media perspective, and I've seen it a lot. There's a lot of scared folks that have simply put in SO many hours with Docker and learning it. Now they're nervous that the time they put in won't pan out.
The time, hours, and passion you put into learning Docker is STILL very much going to be useful. The simple fact is, the whole "runtime not being supported thing" isn't that big of a deal. In fact, some say it was even planned.
Let's start with one key component - Docker is a full stack of tools and isn't just a runtime. Also, Docker != containers.
Docker has so many factors:
2. Docker images
4. Docker compose
5. And many others...
Everything I listed above is still very much going to be used. Docker images can still be created the way they always have been. Dockerfiles can still be used to create those images. The only thing that won't be used is the Docker runtime.
Let's break that down a bit.
Kubernetes uses container runtimes, which include:
Starting at Kubernetes API version 1.20, Docker won't be part of that list anymore. However, Docker has put a TON of time into containerd, which will still very much be used. In fact, Docker created the containerd project for a clean break-away from the core Docker engine.
Really, the only thing that's changing is that middle layer:
Kubernetes <-- Docker <-- containerd Take out "Docker" and you still have everything else. Using the Docker runtime was always a "means to an end" with the growing support of containerd and CRI-O. So, TLDR? The Docker runtime being removed isn't a big deal. In fact, a lot of us probably won't even tell the difference.