During the Algerian War there were actally more Harkis then active FLN fighters. France horribly betrayed them by disarming them and leaving them behind to be slaughtered.
Could France, instead of making a deal with the FLN, played it like South Vietnam and hand over power to their native allies?
The two main problems are probably that France went from "we will never leave" to "get the fuck out of here" in too short a time for an pro-french moderate-nationalist political scene to emerge (//is this correct grammar?) and that the settlers would have fought any form of independence.
But what if the FLN would have been more radical or splintered ionto factions, making any deal with them impossible? France might have decided to create an Algerian goverment out of theri old allies.
But could it have surrvived