Thank you much for the prompt and thorough response.
I find myself in the enviable role of providing technology for a "late adopter" market, namely energy and process automation industries. I long ago determined that my value is largely in getting nifty new services to run on obsolete technology and in somehow keeping obsolete services running over new technology. So, I will confidently state that at some point I will have 15-year deployed legacy equipment on recent deployed RS-485 networks alongside brand-new wireless Hart equipment tied into a redeployed host of some sort, all with expectations of managing them via open hybrid. By the time I universally have broadband networks hooked to high-capability IP equipment, you all will have moved on to something else entirely (or had grandchildren, retired, and so forth).
So I agree with the vision, but add a ball and chain of backward compatibility to it.
As for self-description, to paraphrase Einstein, why would I need to know something about myself if I (and others) can go look it up?
Ideally, where you see self-describing end-points, I will also see an interop gateway with associated descriptions and a legacy device. This seems perfectly fine to me - the "modern" IoT gateway will be like you say, only with a bunch of legacy tendrils out to obsolete devices. I'll build a gateway, and it'll support Modbus, Hart, RS-232, RS-485, analog and digital IO, etc. on one side, and REST/OH on the other. A casual user shouldn't know or care what the physical media is.
Device discovery and acquisition (I can add a new endpoint to my network, but you can't take one of mine over), easy failed device replacement. Zero-touch network add and one-touch initial configuration (a perpetual pain on shared-media networks, like wireless). Compartmentalize and disambiguate if there are 1000s of similar devices in a plant. Role-based views and restrictions (I can only see current data, but you can change a config). Context-sensitive help and context-assisted operations (pull up manufacturers webpage user doc, or shell into my local GUI to do something complex).
Existing specs (like DTM and FDI specs for Fieldbus and Hart networks) have a notion of standardized presentation with a modular approach.
I would much like to. I doubt I will get company support for this, but depending on where things go over the next month or two I may join anyway.