That's nice. seems to be the infrastructure required for building such system. question is how do you come about building the manifests? Users need to do that???
Blueprint is a nice step in that direction: make a change and dump out the environment.
Perhaps what we need is a system that compiles to that manifest, or to chef/puppet.
Setting up systems is a complex task that neither puppet nor chef solve, they make it less daunting, but it still is a real pain to do so!