Supersesionism is true, thus, no Dual Covenant Theory is possible

 

First the Jews, in their capital Jerusalem; 

"And you shall be to me a priestly kingdom, and a holy nation. Those are the words thou shalt speak to the children of Israel."

Exodus 19:6 

But when they voided the covenants via idolatry & sin the Mosaic Covenant was superseded by the New Covenant

"But you are a chosen generation, a kingly priesthood, a holy nation a purchased people: that you may declare his virtues, who hath called you out of darkness into his marvellous light:"

2 Peter 2:9 

And the new holy nation has its Capital in Rome

When Christians leave America to go to Rome they are going to their real Capital