As pointed out by AF Crew Cabin, there are quite a few routes on Air France's network which actually require the capacity for A380s.
Besides, the A380 being an airplane larger and with lower DOCs (Direct Operating Costs) than the 747-400, the aircraft would allow to carry more passengers using the same slots at NRT and JFK for instance (where they are restricted) and with a greater profitability.
As far as the Aerflot's 777-200ERs are concerned, I would like to give a precision: these aircraft have always been maintained by Air France Industrie. Thus, Air France isn't ready to buy anything as an airplane to cope with its growing traffic.
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Photo © Alain Mengus