This does not mean the Law has lost its power. The new covenant fulfilled the Old Testament laws and prophets, but the Law remains (however, compare Acts 15:23–29).
God will cause heaven and earth to pass away and replace them with a new heaven and earth at the end of the age (Revelation 21:1). But God's word lasts forever (Psalm 119:89, 160; Isaiah 40:8; 55:10–11).