I'd revive the Vuldarian concept, allowing at least more of them to have survived and working on increasing their numbers through cloning and genetic manipulation. I'd also bring back the character Veronna who was part of the tribe that guarded the Water of Warriors, but give her the Vuldarian powers. I also think this could make her an interesting contrast for Jaime Reyes - both are humans who have powers of alien origin, but Jaime's are technological while Veronna's are biological.