The Internet and IPv6
The internet obviously uses IPv4 currently and as we all know the world is running out of addresses and the obviously solution to the problem is replace IPv4 with IPv6, however based on the fact that we are talking about the internet and not just some little home network or even something bigger like an enterprise, the issue becomes extremely complicated.
Changing the internet to use IPv6 would probably in actual fact be a total no no because it would be damn near if not completely impossible to complete the task and then the question of the actual deployment would be an issue.