The Lord Jesus taught many vital truths through parables: here we have a wonderful example where He points to the fact that God, in the sending of His Son to die for sinners, is really providing that one and only opportunity for us to believe, and be saved. In the parable itself we can understand that the illustrations Jesus uses can be interpreted as follows: The Landowner/Householder is God; The Vineyard is Israel and Judah; The Vinedressers/Husbandmen are the Jewish leaders; His servants are the Prophets; His Son is The Lord Jesus Christ, and 'A nation bringing forth the fruits thereof' is The Gentiles.
Thus Jesus is teaching that there will be a very significant change; a change that represents a move from strict observance of the OT ceremonial law; to the Grace of God in the Gospel age. The Kingdom of God is now not just to be offered to the Jews in Israel and Judah, but is to be taken to the Gentiles.
In the parable Jesus told, the wicked vinedressers (husbandmen in the KJV) had rejected and killed all those that the landowner (householder) had sent, and had killed them all, even the last hope, the landowner's own son. Are you rejecting God's own beloved Son, Jesus Christ: He is your last, in fact your only hope for Salvation. Believe upon Him and be saved!