Docker is absolutely less relevant. My personal machines haven't run Docker for months and my employer is finishing our migration away from Docker in a few months.

Containers are as relevant as ever, of course.

What's your alternative?

Podman?

For fully serverless (e.g. AWS Lambda) deployments, not even Podman. Just a zip file.

containerd for most use cases including Kubernetes clusters, Podman for some cases where you need Pod-like features but Kubernetes is too much overhead. OrbStack for development, using Tilt instead of Docker Compose.