John,
if I guess correctly you are talking about large grained artifacts as your models, things like ER diagrams and schemas that go on for a couple of pages? I'm talking about fine grained artifacts defined completely in metadata. If you're lucky, the former might live in a repository that can be queried, the latter has to live in a database, it is completely dynamic (though it can be versioned) and a ER diagram produced from it only documents a subset at a particular instance in time. When the model I describe is complete the ontology is part of the same model and in fact describes the metadata for the metadata (among other more conventional artifacts). I am talking about a pretty radical change in the way businesses do modeling, I don't think it would be possible for a large enterprise to do this as recently as two years ago, the technology was there but it would have been too much of a risk to take on at the scale I describe. However, some of the startup world has been doing this for years now and my own version of this first took form to handle clinical research data 10 years ago.
I've talked about that particular metadata driven system a bit here on the list in the past. That system dynamically assembles the metadata (using XSLT in it's case, but good graph manipulation is still hard to come by) to determine how to manage the research data on the fly. If you need an XML schema you can export it from the metadata. The system we built was built on relational technologies to store the metadata and the data and doesn't scale well as a result. Now-a-days graph databases can be used to manage the relationships of data stored in things like Casandra, hBase, Lucerne and ElasticSearch completely on the fly with horizontal replication in the cloud on the fly. It's a different universe than it was 10 years ago; the "insane" has been done and it works. However, I have worked at a phone company with 50k employees and 2k devs in the distant past. Even then they were using a database for the model repository, but yes it would be slow and difficult process to drive this into such an organization and there are parts of that universe where you would likely not want such a system, at least not yet.
I guess I should mention to this list that I am looking for new employment, my current employer has closed their US development shop (and did not even come close to grasping what I describe although they desperately needed it) . So if anyone would like to talk to me about doing any of this as a full time gig or have me talk to them as a consultant please feel free to contact me off list!
