"But it is easier for heaven and earth to pass away, than for one dot of the law to become void(Luke 16:17)."
In Judaism, the law is equated with the Torah. The English word, "law" isn't big enough in scope to mean the whole Torah. The Torah contains the Old Testament, the commandments and the promises, the covenants of God(or G-d if you prefer). To say that Jesus has replaced the Torah is intolerable to Jewish people, and it should be to Christians, too. Jesus did not get rid of the Torah. He didn't get rid of the commandments of Moses. What he did get rid of was the liberal and ritualistic legalism of the modern Scribes and Pharisees.
Some Scribes and Pharisees contrived sayings and rules that made Mosaic commandments easier for them to follow. They were human
suggestions, not true commandments of G-d. The parable of the wineskins illustrates that Jesus did not want to work within that system of human legalism. He would not jump through their hoops. He would follow the Torah, not manmade commands.
This is why Jesus only taught at the synogogue, but never attained a humanly recognized rank of any kind within it. If Jesus had become an official in the synogogue of that time period, it would have destroyed it like new wine in an old wineskin or unshrunk cloth on an old garment. It would be like the Band-Aid method, a temporary fix, and not a very good one. So Jesus started his own synogogue - the church. The
disciples didn't fast much or often(Luke 5:33, footnotes - Matthew 9:14, RSV), because that was a man made rule. In Luke 5:39, Jesus makes a statement about the Pharisees. "No one after drinking old wine desires new; for he says, `The old is good.'" The message is clear: those who love the human based legalism of the Pharisees will never accept Jesus. They love the `old wine' better.
Jesus didn't replace the Torah or commandments. He amended them. He taught how to follow the spirit of the law rather than the letter of the law.
Hebrews 8 says that the new covenant God made with man is better than the old one. However, this doesn't mean the old covenant is to be discredited or thrown out. To say so would indicate that you can't be simultaneously Jewish and Christian.