Now dream, it's a dream, but perfectly feasible technically, where most devs have found and understood the NixOS/Guix System way to develop and manage whole deploy. We would have various distro with different configuration languages like Nix and Guix, and some less diverse, since all devs simply "package", meaning describing, their code in their own distro how hard could be port the derivation/description?

Try also compute how hw requirement for whole infra plunge thanks to an immense overhead avoided on scale. The sole unhappy? Those who sell services, because for that they do need containers. This would push another evolution: built-in easy to tune isolation from a config, so they can sell instead of a VPS a system where you upload just your config, they import it, producing an isolated FHS for you, something we already have (i.e. FHSUserEnv) but with tunable system isolation. You would get your VPS, configured with just few SLoC instead of manually/in wrapped ways via SSH, and they can sell much more on the same iron, with much better performances as well.

All of the above is perfectly possible TODAY, it's only a matter of mass knowledge or lack thereof.