Hmm.. did some research into the number of addresses and came up with this:
IPv4
Over 109 (42 billion)
IPv6
Over 1038 (3.40E38개 ) = 43 billion * 43 billion * 43 billion * 43 billion
http://www.ngix.ne.kr/eng/info/info_overview.jsp
I can't see a future where we have more than 42 billion computers which need a public IP address.