I think your point about the physical world is well made: addresses can be changed (think street renaming), and the core of the UK addressing system, the postal code, is made available on a licensed basis (via the Postcode Address File).

I suppose one potential difference between one’s online residence — a domain name pointing to an IP address assigned to a server, at its most basic — and one’s offline residence — let’s say the ownership of a piece of land — is that the compulsory acquisition of someone’s land, or eviction from a property, is subject to formal processes, and is challengeable before a court. In the online world, one’s protection (if any) is limited to the terms of service governing the relationship between your provider and you. And it probably contains provisions about removal / withdrawal / service cancellation, often without cause. Your protection is only as good as your contractual relationship with your service provider, or perhaps your ability to enforce such a relationship if your services are removed in breach of that contract.

The closest I came to permanence — echoing Dan’s point — was that of a .onion address. There, it is not the operation of a law which offers any certainty, but the mathematics behind the recreation of the private key needed to assert control of the domain. So while the underlying infrastructure may change, your IP addresses become reallocated or whatever, as long as you can get your Tor hidden service connected to the Internet, and do not compromise your private_key file, your address should be reasonably secure. Ironic, perhaps, that a system designed for anonymity / lack of attribution may be the best way of preserving permanence online. For limited values on “online”, and as long as your correspondents don’t mind also being on Tor.