When Palpatine was seducing Anakin to the dark side the main points on his manifesto were his studies into the creation of life and his attempts to achieve immortality. Whilst we know that Yoda, Obi-Wan and Anakin achieved immortality after a fashion, appearing as blue ghosts to Luke at the Yub-Nub celebration on Endor we dont know what twisted, dark methods the Emperor might have discovered to cling on to life. Mutated, artificial flesh and complex cybernetics could create a terrifying, memorable enemy for our heroes in the Sequel Trilogy. Palpatines quest to find eternal life might even lead him to impregnating another woman with the force and taking up residence in the resulting childs body, the body of a child who would be a fully grown adult by the time of the Sequel Trilogys events.