In the first season Enterprise episode Dear Doctor, the Enterprise encounter the Valakians, who it is discovered are a dying race. The more primitive Menk, who share a homeworld with the Valakians are however unaffected.
Phlox discovers a cure, but convinces Archer that they shouldn't interfere with the natural evolution of the two species — allowing the Valakians to apparently become extinct and the Menk to thrive and become the dominant species on their homeworld. Phlox estimated that without the cure, the Valakians would be extinct within two centuries.
Do we ever hear anything of the Menk or Valakian's fate? Either in later episodes of Enterprise or in any of the earlier (chronologically later) series?