Problem is that Gamelin and Georges were on different sides politically, which is also why they didn't really talk to each other (their HQs were some distance apart, and I don't think they were even connected by telephone). So if you dismiss Gamelin, it's almost impossible to replace him with Georges without major political in-fighting in Paris - bringing in someone else over George's head would be easier!Perhaps The Premier should have fired Gamelin back in 1939 and appointed Georges in his place. I believe that the French President was willing to back him against the Defense Minister, Who had been Premier earlier.
That's also why when Georges pointed out that the Dyle plan would collapse if the Germans invaded through the Ardennes (in November 1939), Gamelin pooh-poohed it and ignored him.