If there's a direct sequel to this movie (i.e. something other than Batman vs. Robin and Batman: Bad Blood), the plot will revolve around Rose Wilson (aka Ravager) seeking retribution for her father's defeat.And it'll probably be given the none-too-imaginative title of Daughter of Deathstroke. To better mirror Damian, Rose's age would be lowered to match his, and her story would parallel Damian's Character Development from this movie in that she's torn between playing the part of Daddy's Little Villain (and being praised for it) and forging her own destiny (referencing her eventual ties to the Teen Titans pre-New 52, which Ravager could end up joining—much like Robin did in Justice League vs. Teen Titans—depending on how villainous and sympathetic Rose is portrayed), especially as it becomes apparent Slade really doesn't have his illegitimate daughter's best interests in mind. And since Damian is his father's son, expect a Puppy Love variant of Batman's usual dynamics with Talia to come into play with Damian and Rose's interactions.
WMG / Son of Batman