A Third Testament?

We take it as a matter of faith that the Old and New Testaments contain the whole of the general revelation of God. The Koran, the Book of Mormon, and the wide range of other self-described revelations are not considered to be by Christians. Certainly the content is an issue, but also the concept. I believe that no other book has come along that has contained the words of God, but does that mean that no book could? I am sure that the Hebrews believed that their Scriptures contained the whole of God's revelation, but then the New Testament works came along at the time of Christ. But will God decide to intervene that clearly again in human history?Either at, or before, the final days? And will there be a written revelation of any kind? Or even . . . could there be?