When will prophecies fail? cannot mean "fail to come to pass," for there have always been false prophets. It must mean that they fail to be necessary. The text indicates that the Spiritual gift of prophecy and the Spiritual gift of knowledge (1 Cor. 12:8-10) are only small glimpses of the "big picture," and that when "that which is perfect is come," we will know everything (1 Cor. 13:12). Then, there will be no need for the Spiritual gifts of prophecy and knowledge. But what is it, that when it comes, causes these Spiritual gifts to be no longer necessary? Some say "that which is perfect" refers to the Bible in its completed form, but I seriously doubt those saying that are arrogant enough to say they know everything. No, the Word itself, clearly says it is not until Jesus comes and we meet Him face-to-face, that we will know what He knows (1 Cor. 13:12; 1 Jn. 3:2).
But what about the Spiritual gift of tongues? Will it cease when Christ returns for His Church, or has it ceased to be necessary because of the completed Bible? Obviously, unless the Bible is available in every language, there still appears to be a need for the gift. Also, the Spiritual gift of tongues is a sign gift (1 Cor. 14:22). It is the Jews who require a sign (1 Cor. 1:22). Are there unsaved Jews today? Of course! Will there be unsaved Jews until Jesus comes? Indeed! Therefore, like prophecy and knowledge, there is still a need for tongues.
But the Spiritual gift of tongues needs to be defined. First, it is known languages (Acts 2:4-11). Because the languages spoken were understood by Jews from all over the known world, there was no need for an interpreter. Notice that Peter described the words spoken in tongues as being prophecy (Acts 2:17-18). It is my understanding that tongues, when coupled with the Spiritual gift of interpretation, is the same thing as prophecy (1 Cor. 12:10; 14:5, 13, 27-28). If prophecy is still needed, then tongues, with interpretation is needed. That is why Paul wrote for the Church not to forbid the speaking in tongues (1 Cor. 14:39).
"Let all things be done decently and in order" (1 Cor. 14:40).