It's not on the level of never having to reuse a number, but arguably we've already seen something similar to IPv4->IPv6 (restructuring/numbering to add capacit

It's not on the level of never having to reuse a number, but arguably we've already seen something similar to IPv4->IPv6 (restructuring/numbering to add capacity) in the UK through PhONEday/Big Number Change. Expanding that out to never having to reuse a number, especially now that most people don't have to remember phone numbers (or at least far fewer), doesn't seem that difficult (at least on the numbering end; I don't know about the engineering side of that). https://en.wikipedia.org/wiki/PhONEday https://en.wikipedia.org/wiki/PhONEday / https://en.wikipedia.org/wiki/Big_Number_Change https://en.wikipedia.org/wiki/Big_Number_Change