"Their Internet usage is growing very rapidly, and even they can do the math: If everyone in China needed an IPv4 address - just one - this country would use up one third of the entire public IP address space"

This quote by Vinton Cerf is referring to the quick development of Internet usage in China. Cerf is pointing out that if every person in China were to have just one IPv4 address, it would consume one third of the entire public IP address area. This is a substantial amount of the address space, and it highlights the requirement for more efficient ways of managing IP addresses. Cerf is likely suggesting that IPv6 needs to be adopted in order to accommodate the growing number of Internet users in China. IPv6 is a more recent version of the Internet Protocol that provides a much bigger address area, enabling more effective use of IP addresses. Cerf's quote is a pointer of the value of effective IP address management, and the need to keep up with the growing need for Internet gain access to.