There are several prophecies in Isaiah that are unfulfilled. This does not make them contradictions. These prophecies are still future. Let me show you a great example from the book of Luke. In Luke 4 it says this:
16 And he came to Nazareth, where he had been brought up: and, as his custom was, he went into the synagogue on the sabbath day, and stood up for to read.
17 And there was delivered unto him the book of the prophet Esaias. And when he had opened the book, he found the place where it was written,
18 The Spirit of the Lord is upon me, because he hath anointed me to preach the gospel to the poor; he hath sent me to heal the brokenhearted, to preach deliverance to the captives, and recovering of sight to the blind, to set at liberty them that are bruised,
19 To preach the acceptable year of the Lord.
20 And he closed the book, and he gave it again to the minister, and sat down. And the eyes of all them that were in the synagogue were fastened on him.
21 And he began to say unto them, This day is this scripture fulfilled in your ears.
You will notice that the quote is from Isaiah 61:1-2. However, open Isaiah 61 and notice that Jesus stopped reading halfway through verse 2! The second half of the verse describes “the day of vengeance,” which is still in the future! Jesus only fulfilled the first part of the verse, “proclaiming the acceptable year of the Lord,” at his 1st coming. He will fulfill the 2nd half of the verse at his 2nd coming.
So, what you have are several prophecies in the old testament that have not been fulfilled YET. But you can safely rest assured that those prophecies will be fulfilled someday in the future.
“For verily I say unto you, Till heaven and earth pass, one jot or one tittle shall in no wise pass from the law, till all be fulfilled.” – Matt. 5:18
This is not a contradiction.