Sunni Muslim scholars have given many different reasons for the return of Prophet Jesus عليه السلام to this World. A few are listed below:
1) The Jews believe that they killed Prophet Jesus عليه السلام , Allah will send him before the end of time to prove that they did not killed him and that he is alive. It is Jesus who will fight the Jews and kill their leader, the Dajjal. (Ibn Hajar Al'Asqalani's
Fathul-Bari)
2) Some scholars have said that Prophet Jesus عليه السلام found many virtues of the followers of Prophet Muhammad صلى الله عليه وسلم in the Bible and thus he prayed to Allah to make him amongst the nation of Prophet Muhammad صلى الله عليه وسلم . Allah answered his prayer and he will return for the second time as one of the followers of Prophet Muhammad صلى الله عليه وسلم . (Ibn Khathir)
3) It is the Law of Allah that anything created from the Earth has to be buried in the Earth and not in the Heavens. Thus, he will return to the Earth for the second time, kill the Dajjal, live for a period of time and then he will die a natural death and will be buried near the Prophet Mohammad صلى الله عليه وسلم . (Muhammad Al-Barzanji's book
Al-Isha'ah li Ashrat AsSaa'h).
http://www.discoveringislam.org/return_of_jesus.htm