There is a big difference between God prophesying about American specifically, and some passages of Scripture describing situations that may be likened to the current situation in America. The latter is a result of human (sin) nature and the progress of God's timetable. It is not proof that God wrote about America in Scripture.
Gen. 22:17, 18 "That in blessing I will bless thee, and in multiplying I will multiply thy seed as the stars of the heaven, and as the sand which is upon the sea shore; and thy seed shall possess the gate of his enemies; And in thy seed shall all the nations of the earth be blessed; because thou hast obeyed my voice."
God's physical promise to Rebekah:
Gen. 24:60 "And they blessed Rebekah, and said unto her, Thou art our sister, be thou the mother of thousands of millions, and let thy seed possess the gate of those which hate them."
It was during the latter 18th century, when Britain rose to world dominance, with their navy controlling most of the seaways. The United States rose to a world power after the war with Spain, circa 1898. What other countries controlled the world’s sea gates: Suez, Gibraltar, Hong Kong, Singapore, South Africa’s horn, the Falklands, Panama Canal, Puerto Rico and Guam.