You still need at least one IPv4 address somewhere if you want to send ICMP back, yes. (Typically a loopback, i.e., something not connected to a specific interface. Routers use loopback interfaces for rather different purposes than a Linux workstation.) But you don't need to set up an IPv4 address on every interface, so you don't need a linknet plan.
You can also forego the IPv4 addresses entirely, but then traceroute (and presumably also stuff like Path MTU Discovery; have consistent MTUs!) won't work. traceroute is often broken for entirely different reasons, though.
You can also forego the IPv4 addresses entirely, but then traceroute (and presumably also stuff like Path MTU Discovery; have consistent MTUs!) won't work. traceroute is often broken for entirely different reasons, though.