In The Name Of Allah Most Gracious Most Merciful
Assalaamu alaykum wa rahmatuallahi wa barakatuhu
 

As long as Quraish stick to the rules and regulations of the religion (Islam)

Sahih Al-Bukhari HadithHadith 9.253 Narrated byMuhammad bin Jubair bin Mutim

That while he was included in a delegation of Quraish staying with Muawiya, Muawiya heard that ‘Abdullah bin ‘Amr had said that there would be a king from Qahtan tribe, whereupon he became very angry. He stood up, and after glorifying and praising Allah as He deserved, said, “To proceed, I have come to know that some of you men are narrating things which are neither in Allah’s Book, nor has been mentioned by Allah’s Apostle . Such people are the ignorant among you. Beware of such vain desires that mislead those who have them. I have heard Allah’s Apostle saying, ‘This matter (of the caliphate) will remain with the Quraish, and none will rebel against them, but Allah will throw him down on his face as long as they stick to the rules and regulations of the religion (Islam).

*Note:Caliphate will remain with the Quraish till they follow rules and regulatiosn of Islam,but if they deviate then rebellions may suceed.

Allah Knows Best