And him whom We grant long life—We revert him to a weak state in creation. Will they not then understand? (36:69) more translations
This verse describes the process of ageing as an unstoppable natural phenomenon from which no man is exempt. Jesus would be subject to its sanction just like anyone else. Having once reached physical maturity and prime, he would have steadily aged and grown weaker over the years before becoming an old man. Not long after that he would have met his death. There is nothing remarkable in that. His fate could be no different to any other human being. However, if we are to believe that he is still alive as he incredibly steps into the third millennium of his life, then according to the verdict of this verse, his physical and mental faculties would be in a state of such advanced decrepitude that his existence would be utterly meaningless. That is the only form of life which this verse would allow him: a life that is indistinguishable from death itself.