Not sure what you mean. The current European superchargers use a Type 2 Mennekes adapter, but the protocol is proprietary.

I gather that European Model 3s will have CCS sockets (a superset of pins of Type 2 Mennekes) so they will be able to charge at other networks' stations.

They already have, as the Model 3 started deliveries in Europe in February. There are thousands of Model 3 in Europe by now :)