The West will assimilate other civilizations and then will decay

Arnold J. Toynbee : historian
The Western civilization, one of the remaining four, will assimilate the Far East, Hindu, and Islamic civilizations or it might develop as a "Universal State" after its "Time of Troubles'. Then it will decay and die.

Toynbee, Arnold. 1935-1961. A study of history. London: Oxford University Press, H. Milford.