In any case, the faith that now saves is open to any person of any nationality....
Actually salvation come by 'the way' it always has. By following God's commandments. It is true though that it comes tho those of any nation, and ANY faith, AS LONG AS THEY FOLLOW GOD'S COMMANDMENTS. God doesn't change.
Genesis 26
4 And I will make thy seed to multiply as the stars of heaven, and will give unto thy seed all these countries; and in thy seed shall all the nations of the earth be blessed;
5 Because that Abraham obeyed my voice, and kept my charge, my commandments, my statutes, and my laws.
6 And Isaac dwelt in Gerar:
Take a look at these two verses:
Romans 11
26 And so all Israel shall be saved: as it is written, There shall come out of Sion the Deliverer, and shall turn away ungodliness from Jacob:
As it is written. To what does Paul refer?
Isaiah 59
20 And the Redeemer shall come to Zion, and unto them that turn from transgression in Jacob, saith the LORD.
Do you notice the difference?