[em-bee]

MAC addresses being random is a historical accident (because of hardware limitations). today we can define them in software. and just like we have link-local addresses we could self-assign link-local MAC addresses.

and i think the self assigning protocol in link-local could even go a step further. instead of hard coding a subnet, it could detect the subnet by copying the one from its nearest neighbor. so start with a random address, talk to neighbor to learn the subnet (and netmask) in use and switch to a new address within that subnet. then possibly run DHCP and update the address again. for static addresses DHCP could identify hosts by its cryptographic host key (like the one for SSH)

when two subnets join one of them may have to adjust its prefix. more complex, but still possible.

subnet prefixes could still be assigned to organizations to avoid overlap on a global level.

i am sure i am missing some details but i think in general this could work.

[sirtaj]

This sounds suspiciously close to re-inventing ARP and IP.

[em-bee]

well, it's merging MAC and IP into one address. there is no need for two if the MAC address can be assigned dynamically. and it's extending the auto-discovery of the address to work over larger networks. so it's not reinventing but simplifying things. (or not, i am not familiar enough with the details to be aware of other problems that could complicate things again)