A change of priesthood had a change of law. The Levitical priesthood was ancestral. The new priesthood centered around an indissoluble life. Jesus our Melchizedek was declared a priest for ever.
The old priesthood did not include a descendant of Judah, which Jesus was. The Law must change and it did. God took away the priesthood Moses instigated. This was introduced by Jesus at the Last Supper. The Passover Feast ended forever, the Levitical priesthood ended forever and the Old Covenant , Mosaic ended forever. The geneologies of the priesthood were destroyed by fire in A.d.70. There was then: a. The end of God’s pohysical, natural, earthly people, Israel – forever. b. A destroyed temple, priesthood, institutions, sacrifical system. c. No more special privileges to that Israel nation of the Old Testament. Thus began the times of the Gentiles, in which times we still are. These times remain until the second coming of the Lord Jesus Christ when the trumpet sounds, the dead are raised incorruptible and all believers are changed and given bodies of immortaity, with glory as is the body of Jesus.