I will therefore make a conditional statement. Your argument for not translating the word 'sabbatismos' as 'Sabbath keeping' is illogical and unpersuasive. (Illogical because your using translations to back up your argument without knowing a single reason from these translators as to why. Disagree or not, its irrelevant to me.) However, I will not contend this for the duration of this discussion. From here on, "Sabbatismos" should be translated as either 'rest' or 'Sabbath rest'.
OK
Now, why should we not interpret this Heb 4:9 passage to mean that since the millenial rest has not come there remains a Sabbath rest, meaning 7th day rest, for the people of God?
Jesus says to enter into
his rest. (Mt 11:28). He is Lord of the Sabbath (Mt 12:8)
Note how Matthew's narrative moved quickly from Jesus saying “Come to me, all you who labour and are burdened, and I will give you rest” to ”For the Son of Man is Lord of the sabbath.”, only 9 verses later.
Jesus is saying we find our (sabbath) rest in him.
Note what follows Heb 4:9. We must not take it in isolation
Vs 9 “Therefore, a sabbath rest still remains for the people of God.”
Those of the OT did not find God’s rest even in the Sabbath. Therefore we will not find it in the Sabbath either.
Vs 10 “And whoever enters into God’s rest, rests from his own works as God did from his.”
We are to enter God’s rest. Jesus is God and entering Jesus’ rest (Mt 11:28) is how we now enter God’s rest.
Vs 11 “Therefore, let us strive to enter into that rest, so that no one may fall after the same example of disobedience.”
We would not be asked to strive to enter that rest if it were no possible to do so
now. We enter it by obedience to Jesus.
Here are my responses to a couple of previous points you made:
Fulfill and destroy can't mean the same thing in practice. By that I mean you can say they are fulfilled so I don't have to do them, which would be the same results of them being destroyed, they're destroyed so I don't have to do them. His words would be meaningless if this was the case. This is why he later said great in heaven beef those who do those commands and teach those commands to others.
There is a lot of difference between fulfilling and destroying.
If I offer to buy something I enter into a contract with the seller. I pay some money. The seller provides the goods. When I have paid for and received the goods the contract is fulfilled.
If there is a warranty then the contract is not fulfilled until the end of the warranty period. But when that is reached the contract is fulfilled. It has no claims on myself or the seller.
The contract was not destroyed it was simply fulfilled and came to an end.
Destroying the contract would be tearing it up before it had been fulfilled.
There is a problem here that you've not mentioned. None of the signs discontinued when a new covenant was made, up until the New Testament some would argue. I still see rainbows. Circumcision continued into the Mosiac covenant as well as rainbows. The trend seems to be that signs don't stop even with a new covenant made and the old one starts to degrade.
You are assuming that each covenant replaces the previous one.
The covenant with Noah is still in place. God will never again flood the whole earth.
“I will establish my covenant with you, that never again shall all bodily creatures be destroyed by the waters of a flood; there shall not be another flood to devastate the earth.” (Gen 9:11).
The covenant with Abraham was not superseded by the covenant with Moses. The promises that God made to Abraham had yet to be fulfilled. The Jews were still under the Abrahamic covenant and so circumcision was still an operational sign.
