The Sabbath promoters may not change--that seems clear. I think God could've made it clearer simply by stating, through his Apostles, that the entire Law, with all of its commandments, died with the failed covenant given through Moses.
In fact, they did say this to some degree but may have left some ambiguity for those who wished to ignore Faith and follow, instead, the path of Legalism. The argument Paul gave against the Legalists is clear--God's covenant of Law is eternal, for "all your generations." But it was a temporary Covenant and not an eternal Promise.
Of course, a covenant can be a perennial requirement associated with a particular covenant, and not a promise that all parties would succeed in that covenant. We are told in Scriptures that this Covenant of Law would in fact fail, indicating that the requirements, along with their promises, would suffer loss.
It is to be noted that the Legalists always quote the perennial nature of the Law for Israel but never quote the conditional nature of the Law--the fact that the Covenant of Law would fail! And they never quote how the Covenant was only for Israel, and not for the whole world.
So, without the Covenant of Law all that remained was God's original mandate for Man, to faithfully present His image, along with the eventual promise of restoration for those who conform and are thus pardoned. Final righteousness, then, did not come from the Law, but rather, Jesus provided in his own perfect example a means of forgiveness from God, substituting for our shortcomings his ideal life.
Though the Covenant of Law was irretrievably broken, God's righteousness and mercy lived on through the Grace poured out on us through Jesus Christ. To return to the Covenant of Law, is to confine righteousness to Israel. And even worse, it is to condemn all to the eternal failure that Israel exemplified.
We now live through Christ, and Christ alone. All parts of the Law were fulfilled in his life. And he had absolutely no need to live by a Law of Redemption, such as was the Law of Moses.