It is an interesting proposition that you have proposed.
The understanding of the Jews is that Melchizedekel is that he is also Shem, the eldest son of Noah, who, on Noah's death inherited Noah's authority over all of the People of the earth at that time and also became a Priest unto God for all of the people of the Earth.
The Twelve princes of the 12 tribes of Israel also operated under the same principle as Shem operated as a priest between the people and God. The dedication of the Sanctuary of the Tabernacle was carried out by the Princes of the twelve tribes of Israel, see Numbers 7, in the pattern portrayed by Shem, as Melchizedekel in Genesis 14. The covenant entered into by God with the 12 tribes of Israel at Mt Sinai was that they would become Priests unto the Lord in the Order of Melchizedekel as the covenant entered was to establish a kingdom of Priests and a Holy Nation unto the Lord.
Christ became the first Priest unto God at the beginning of the Millennium Age in the order of Melchizedekel as given at Mt Sinai and when God made like new again the Mt Sinai covenant of a Kingdom of Priest and a Holy Nation, Israel too will be a kingdom of Priests operating in the Order of Melchizedekel as well.
As a Kingdom of Priests, the role of the Nation of Israel will be to operate as a priest to instruct the people living about each of the Priest of the Kingdom of priest covenant that is to be renewed in our near future about the Salvation Covenant that existed at the time that Adam and Eve were formed at the end of the sixth "period of time" during the creation story and has now been refurbished and made like new again for all of the people of the earth to respond too.
The "Old" and the "New" covenant will fade in their significance as the Salvation Covenant is preached for the salvation of the lost Souls being drawn into God's everlasting Kingdom.
This is a very different understanding of God's Salvation covenant with Mankind.
