Oh, the Sabbath hasn’t changed, and it’s made clear in the Bible that it is an eternal ordinance (Exodus 31:16)—same with the annual Sabbaths such as passover, days of unleavened bread, day of atonement et cetera. The breach of same is but one of the sins that got both Israel and Judah cast into captivity, and don’t think it won’t get the USA, Britain and the rest of professing Christendom punished for its breach. The scripture cannot be broken.
The wages of all sin is still the death penalty—Paul makes that clear in Romans 6:23, as well as the way to become free of that death penalty, which is the reason Jesus died. The ten commandments all stand; Jesus Himself was clear on that point, otherwise He would not have told the rich young man so (Mark 10:19, Luke 18:20), and He is the same throughout all time (Hebrews 13:8). As for cursing father and mother and dying for it, take note that Jesus upbraided the Pharisees for allowing people to get away with such cursing.
Well got at least give you credit for consistency when saying that the Saturday sabbath obligation ought to transfer over to the Gentile segment of the church... even if you in fact are wrong at least you are trying to be consistent.
And I believe in fact you are wrong. Acts 15 is definitive for the Gentiles. The way to step into the Jewish grace would be to become actually Jewish. The arguments for saying that Judaism transfers over to the Gentile church are so weak that they make far better sense as illustrations of holiness (the Jews were a special exhibit of holiness).
Also this parsing apart of the Mosaic covenant alone shows how suspect that approach ought to be as something which is blocking grace, rather than enabling grace. The Mosaic law is atomic, inseparable; the bible is very clear on that. You can’t go parsing in it. All or none. It served as a framework for a special exhibit of holiness during the early stage of God’s teaching the world. If not kindergarten, then at least early primary.
You also have the audacity of predicting punishment for Saturday sabbath breaking when the New Testament says it is OK to treat all days alike. There is divinely offered choice of ceremonial framework here, friend; no ifs, ands, or buts about it. It might be beneficial to some to go Jewish in a Christian framework. But friend, grace is the audacious thing. Not punishment.
In fact let me even be audacious about the role of punishment! It’s only to make us aware of the need to be in the light. Nobody can pay for their own sins, not even in hell. Christ came to show that and to solve that problem simultaneously... with grace. To deny that paradigm is to deny the very taproot of Christianity.