Still confusing?
It is looking as though anyone who travels within the EU still needs two SIMs.
One for your home country to roam at will in the rest of the EU, and one from any other EU country to call cross border at local rates when you are at home.
I assume the original aim was for all calls within the EU to be charged as national calls.
So for example if you flit between France and Belgium you will still need two SIMs, you just change which calls you make with which SIM.
ISTR that there are supposed to be measures which govern how long you can roam with a SIM to try and prevent this cost optimisation.