Normally it is left to the airlines to reduce their programmes by the appropriate percentage. They will keep the most profitable routes and cancel the low revenue ones. The Spanish government will probably insist that the islands are served (Canaries, Ballearics) normally by determining a minimum service. The exact details should be issued soon.
Oh, and by the way, the French have extended their industrial action until the 30th September.
Details will be available here;
EUROCONTROL - Central Flow Management Unit (CFMU)
Click on CFMU NOP Public