"Sure it does:
the Paraclete, the Holy Ghost, whom the Father will send in my name, he will teach you all things, and bring all things to your mind, whatsoever I shall have said to you. [...] 30 I will not now speak many things with you.
(John 14)
Note the future tense."
Yes and here is what Jesus was talking about. You really have to compare scripture with scripture to get the full picture, you can't just pull "proof texts" out of context that are explained in other scripture.
John 20: 30-31, "And many other signs truly did Jesus in the presence of his disciples, which are not written in this book: But these are written, that ye might believe that Jesus is the Christ, the Son of God; and that believing ye might have life through his name."
The conjecture that the "signs" in John 20 are the entirety of the teaching that the Church received from the Holy Ghost as promised in John 14 is yours. It is not in the scripture, and in fact is contradicted by the wording and context of John 14, where Christ speaks of teaching rather than of signs, that is, miracles and actions.
Further, the purpose of the gospel as stated in John 20:31 is to furnish proof of divinity of Christ; it does not say that everything necessary for the Christian faith formation, "for the salvation of man and fellowship with Him" is contained in it. At any rate, you asked if revelation exists outside of scripture, and John 20 and 21 directly state that yes, there was such revelation given the Apostles.