There are also still Telex and X.25 networks around there, not to forget the whole public telephone network!

But at some point, getting a native connection to all of these started becoming increasingly rare, and now these are largely emulated/tunneled on top of IP. The same can happen for IPv4.

> IPv4 will be around for longer than you or I.

That's a matter for the legacy network on the other side of the internet to handle, as it converts my IPv6 packets to IPv4.