[gorgoiler]

I missed the edit deadline and wanted to add:

So instead of talking about there being 2^128 addresses, it’s more useful to talk about there being 4k global regions (/12 RIRs), assigning /32s to ISPs in their region.

Each ISP can assign a /48 to each customer site, which can then subdivide into 256 buildings with 256 VLANs each (or some other balance of the these, eg 8 buildings with 64 floors each and 128 VLANs on each floor) with the hosts selecting randomly (or SLAACly) from the final 64 bits.

Some ISPs where customers are in a single dwelling will only give you a /56.