If a provider no longer offers public IPv4 addresses, then a VPN tunnel that couples IPv4 networks can also be established over IPv6 WAN addresses.
This requires IPv6 addresses to be configured for the VPN gateway addresses.
In the example shown, two local IPv4 networks are connected via an IPv4 VPN tunnel, which is established over an IPv6 Internet connection. The IPv4 VPN packets are given IPv6 headers and sent to the remote site via the IPv6 Internet connection (either native or via tunnel broker).
