Elementals: the Next Generation

It has been many centuries since the last human left Earth, believing it to be a dying world. The Elementals have continued their mission of undoing the damage they have left. However, one of them thinks that perhaps there is a possibility of there being other Elementals on the new plants that have been colonized and wishes to bring these individuals back to Earth. The others are convinced that this would spell disaster for Earth. Could they be right?