Do Deuteronomy 29:29 and Isaiah 59:21 teach that the Mosaic law was meant to be followed forever?

Deuteronomy 29:29 KJV >The secret things belong unto the Lord our God: but those things which are revealed belong unto us and to our children **for ever, that we may do all the words of this law.** Isaiah 59:21 > “As for me, this is my covenant with them,” says the Lord. “My Spirit, who is on you, will not depart from you, and my words that I have put in your mouth will always be on your lips, **on the lips of your children and on the lips of their descendants—from this time on and forever**,” says the Lord. Do these verses prove that Old Testament law is still to be followed since it is to be followed forever?