Ok. How do you increase address space without breaking the protocol? IPv4 just doesn't have the space in the header. Something like "v4+" can't happen for this

Ok. How do you increase address space without breaking the protocol? IPv4 just doesn't have the space in the header. Something like "v4+" can't happen for this reason. You could argue that pervasive use of NAT beginning in the late 90's was "v4+". It bought us decades of Internet growth, at the expense of true end-to-end connectivity.