Safeena RA reports that Rasulullah SAW said:
"The Khilaafat will last for 30 years; thereafter Allah will grant kingdom to whomsoever He wishes." (Sunan Abu Dawud, Sunan Tirmidhi, Sahih Ibn Hibbaan)
The Khilaafat above refers to the age of the Khulafa Ar-Rashideen. The prophecies of Rasulullah SAW have never defied reality. All have become true. The caliphate of the Khulafa-Ar-Rashideen did in fact last for 30 years - from the tenure of Saiyidina Abu Bakr As-Siddiq RA to the caliphate of Saiyidina Ali ibn Abi Talib RA.