I love NixOS and was a nixpkgs committer. I think a lot of ideas from Nix will get adopted by the wider Linux ecosystem. But I think it is far more likely that immutable systems based on OSTree, like Silverblue and Fedora CoreOS will become the OS for the next 20 years. It is much more familiar to most people and provides many of the same benefits. Especially now OSTree is adopting Docker/OCI images as a transport [1], the line between building systems and building containers is blurring. A lot of organizations have plenty of institutional knowledge in building Docker containers and OSTree with containers makes system building pretty much the same.
