From Day One, it is suggested the Island is special in many ways. I have a theory about one of them.
Many people have noticed that the 'Canton-Reinier' written on the side of the van which briefly held the body of John Locke is an anagram for 'reincarnation'. This suggests (pretty strongly) that Locke will sometime return to life. Since they are taking his body back to the Island, how about then? What if, whenever a corpse is taken to the Island, life returns to it? Does anybody remember Christian Shephard? A few days after the crash of 815, Jack ventures to his father's coffin and finds it empty. Throughout Lost, Christian is seen, fit as a fiddle. Although it's never confirmed he is acually there (and not a vision/apparition), I think he is truly alive and tangible. Which is why I think we haven't seen the last of John Locke.