Exo 12:48-49 And when a stranger dwells with you and wants to keep the Passover to the LORD, let all his males be circumcised, and then let him come near and keep it; and he shall be as a native of the land. For no uncircumcised person shall eat it. (49) One law shall be for the native-born and for the stranger who dwells among you."
This passage gives specific instructions on how a Gentile would become a part of the people of God and included in the Mosaic Covenant. They would have to be circumcised and would have to keep the Law and the Passover. Verse forty-nine is very specific. It says that the mosaic law applies to the Jew and the Gentile. Therefore, a Gentile could become a Torah observant Jew.
The jots and tittles that made up this particular passage of the Mosaic Law did in fact disappear in the first century. This is assuming that the New Testament is scripture and instruction from God. They disappeared with the letter written by the apostles found in Acts fifteen. Act 15:24-29 Since we have heard that some who went out from us have troubled you with words, unsettling your souls, saying, "You must be circumcised and keep the law"—to whom we gave no such commandment— (25) it seemed good to us, being assembled with one accord, to send chosen men to you with our beloved Barnabas and Paul, (26) men who have risked their lives for the name of our Lord Jesus Christ. (27) We have therefore sent Judas and Silas, who will also report the same things by word of mouth. (28) For it seemed good to the Holy Spirit, and to us, to lay upon you no greater burden than these necessary things: (29) that you abstain from things offered to idols, from blood, from things strangled, and from sexual immorality. If you keep yourselves from these, you will do well. Farewell.
In this letter, the apostles have indeed established that not only have jots and tittles disappeared but, in fact an entire passage is eliminated. The Gentiles are made the people of God by faith in Jesus Christ and not by circumcision and law observance. Therefore heaven and earth must have passed and all must have been fulfilled. Otherwise Jesus statement in Matthew 5:18 is untrue.