Louis' plantation is burned, he has disappeared, and the slaves are celebrating with torches. It's doubtful anyone will believe that he called himself the devil and freed them before burning the house himself. It's likely that if they are caught, they would be painfully executed.
Being familiar only with the book, where Louis feeds off of his slaves (and murders them all, rather than freeing them), there is some possibility that the outcome could be more positive. Although the actual events occurred a few decades later under different circumstances and under US rather than French control, there's some precedent for a truly, abominably, sadistic slave owner in Louisiana being rejected even by the horrible standards of their time. Given what happened, it may even be the inspiration for what occurs in the film. In the 1830s, Madame Delphine LaLaurie was a slave owner and popular socialite who tortured her slaves to the extent that one of them (who was chained to the stove in her kitchen) attempted suicide in order to avoid her anger by starting a fire. The fire was put out by her rescuers, who found evidence of LaLaurie's continued abuse after a prior incident where she'd had her slaves taken from her following what the historical record disturbingly calls illegal cruelty. The community responded with outrage. Assuming that there's evidence left behind following the fire, and that the slaves aren't massacred too soon for it to matter, it's possible that Louis will be treated the same way. At least in the novel, he's concerned enough about the possibility to kill them to avoid survivors recounting what he did.
Fridge Brilliance
When Louis first meets Santiago, he is "mirroring" Louis's movements, before disappearing and reappearing behind him. When Louis has to fight Santiago during the burning of the theatre, Santiago again begins by mirroring Loius's movements... so Louis knows that Santiago is going to end up behind him.
