The prince's sister, Princess Sirindhorn, is more popular than her brother, and the Thai Constitution allows princesses to be appointed successor if there is no male heir apparent. Most constitutional scholars believe that King Bhumibol could appoint his daughter as his successor if he chose, but he has not made any indication that he will do so.
King Bhumibol's Life and Legacy
Although he was never intended for the throne, Bhumibol Adulyadej has been a successful and increasingly beloved king of Thailand over the many decades of his reign. Superficially his life seems similar to other monarchs, such as Japan's Emperor Akihito; both are semi-divine, have a life-long interest in science, enjoy art and music, etc. However, unlike the current Emperor of Japan, Bhumibol plays a significant if shadowy role in the politics of his realm.