You don't get it do you? The first 800 years of the existence of the Caliphate it was ruled by Arabs in Arab land. From the death of Prophet Muhammad (saws), through the greatest and biggest conquest of non-Muslim land, to the Golden Age of Islam to basically the founding of Islam.
Learn about Islam before you speak. Makkah and Madinah are the two holiest cities in Islam. Al-Quds is the third. Obviously they are 1000 times a more fitting place for a real Caliph than any other city.
If you look what I wrote initially in that post, you did not quote that part, strange, then I said that it would not matter which ethnic group the Caliph came from. Moreover I already proposed that the Caliphate, should such a thing ever materialize, that it will be shared by all Muslims countries as every Muslim country could have leading clerics representing them and they would in turn be chosen one after one so each Muslim country "ruled" the Islamic world at least once every 20-30 years.
Currently no other person have even come up with an other alternative other than talking nonsense.