If the French IR is
ICAO compliant, then it will be usable
worldwide subject to
(a) any restrictions imposed by the State of Registry (France, if the IR is limited to F-regs), or
(b) any restrictions imposed by the owner of the airspace (this category is very rare*, otherwise ICAO would be largely meaningless).
* outside of 3rd world dictatorships like the EU which is proposing to do just that if the operator is based in the EU
So, all depends on whether the final French regulation actually limits it to French airspace.
They are talking of limiting it to French issued PPL holders, which de facto means French residents.
With this precedent, I guess the UK can keep the IMC rating as well, valid in the UK only...
Well, yes, France has realised that if they stick a finger up to Brussels, nothing is actually going to happen. The gradual EU meltdown is probably working in our favour... nothing would be worse than a strong central EU government.