All oppressive regimes will disappear in the time of Hazrat Mahdi (as)
Ali Ibn Ibrahim relates from Shahr Ibn Havshab: ... “THE PROPHET ‘ISA (AS) WILL DESCEND TO EARTH BEFORE DOOMSDAY. THUS THERE WILL BE NONE FROM AMONG THE JEWS AND NAZARENES WHO DO NOT BELIEVE IN HIM BEFORE DEATH (BEFORE THE PROPHET ‘ISA (AS) DIES OR BEFORE ANY FROM AMONG THE JEWS AND CHRISTIANS DIE). THE PROPHET ‘ISA (AS) WILL PERFORM THE PRAYER (SALAT) BEHIND HAZRAT MAHDI (AS). Hajjaj asked: “What are you saying? How do you know this?!” “It is a hadith,” I said. “I heard this hadith from Muhammad Ibn Ali Ibn Husayn Ibn Ali Ibn Abu Talib!” At that, he said, “I swear you have heard it from the most accurate source!”
(Qummi Commentary, Vol. 1, p. 158)
Our Prophet (saas) interpreted the verse “There is not one of the People of the Book who will not believe in him before he dies; and on the Day of Resurrection he will be a witness against them” (Surat an-Nisa’, 159), as indicated in the above hadith.