If you read this section, the author gets a lot of things right, but clearly doesn't know the space that well since there have been people building things along these lines for years. And making vague commentary instead of describing the nitty-gritty doesn't evoke much confidence.
I work on one such language/tool called mgmt config, but I have had virtually no interest and/or skill in marketing it. TBQH, I'm disenchanted by the fact that it seems to get any recognition you need to have VC's and a three-year timeline, short-term goals, and a plan to be done by then or move on.
If you're serious about future infra, then it's all here:
https://github.com/purpleidea/mgmt/
Looking for coding help for some of the harder bits that people might wish to add, and for people to take it into production and find issues that we've missed.
And not only because of legacy systems that are hard to migrate to a modern platform. At my place of work there are workloads that can easily run on Kubernetes and it would be wise to do so. On the other hand there are systems that are not designed to run in a container and there is frankly no need to, because not everything needs to scale up and down or be available 100% of the time at all costs.
I think configuration management systems like mgmt (or Ansible and Puppet) are here to stay.
I think so too, however "mgmt config" builds a lot of radical new primitives that Ansible and Puppet don't have. It's been negative for my "PR" to classify it as "config management" because people assume I'm building a "Puppet clone", but I really see it as that space, it's just that those legacy tools never delivered on the idea that I thought they should have correctly.