Okay, so all the laws concerning the priesthood have been changed, however the Hebrew festivals were conducted by the Levitical priesthood. So your logic is flawed. Also grace precludes true believers being under the Law.
John 1:17
17 For the law was given through Moses, but grace and truth came through Jesus Christ.
NKJV
Romans 5:20-21
20 Moreover the law entered that the offense might abound. But where sin abounded, grace abounded much more, 21 so that as sin reigned in death, even so grace might reign through righteousness to eternal life through Jesus Christ our Lord.
NKJV
Romans 6:14
14 For sin shall not have dominion over you, for you are not under law but under grace.
NKJV
Galatians 2:21
21 I do not set aside the grace of God; for if righteousness comes through the law, then Christ died in vain."
NKJV
Galatians 5:1-6
Stand fast therefore in the liberty by which Christ has made us free, and do not be entangled again with a yoke of bondage. 2 Indeed I, Paul, say to you that if you become circumcised, Christ will profit you nothing. 3 And I testify again to every man who becomes circumcised that he is a debtor to keep the whole law. 4 You have become estranged from Christ, you who attempt to be justified by law; you have fallen from grace. 5 For we through the Spirit eagerly wait for the hope of righteousness by faith. 6 For in Christ Jesus neither circumcision nor uncircumcision avails anything, but faith working through love.
NKJV
You can read the above in there full context to see that you are dead wrong.