Nowadays, the whole of Indochina is pretty independent. Besides some meaningless symbolic gestures they have pay to the French Republic, the whole federation of Indochina did gave way much autonomy that eventually led to independence. Perhaps this was a necessary evil to safeguard to protect these regions from communism. The French fought a brutal war that lasted nearly 20 years starting from 1946 to 1964 to suppress these communist guerrillas, this war was fierce, many French commanders at the time thought seriously the French would be defeated. It didn't help that France was a broke nation due to the aftermath of World War 2.
I am thinking of something that can shift the power balance towards the Communist guerrillas more, perhaps the Nationalist China losing its civil war to the Communists there. With the Mainland completely under the control of the Communists, the Communist guerrillas would have basically an unbroken supply lines to attack the French and even a sanctuary. The Soviets attempted to supplied the Communist guerrillas in Indochina but they didn't have really way to supply them with heavy weaponry like big artillery pieces. They couldn't supply them enough to affect the French war effort much and not to mention Soviet aid came in too late.