I don't see a narrative change. Jesus and Nicodemus are having a deep and meaningful late night discussion about the nature of salvation, rebirth and the meaning of being 'born again.' I don't see a change from 15 - 16. I know that some bible versions have the 'red letters' on 16, meaning those words were spoken by Jesus, while other versions do not. Interpreters / translators have disagreed.

When reading the NT, my favorite version is Kenneth Wuest's Expanded Translation of the New Testament. If you're not familiar with it, Wuest wanted to write this because he saw the need for a translation that encompassed the real meaning of the words - with all the grammatical and other nuances - from the Greek to English. So he wrote a translation that uses as many English words as necessary to convey what the original language says. He also kept it in word order as much as is necessary. Let me give you an example. The very famous Hebrews 13:5, where God assures us that He will never abandon us is translated this way by Wuest. (verses 5-6) "Let your manner of life be without love of money, being satisfied with your present circumstances. For He Himself has said, and the statement is on record, 'I will not, I will not cease to sustain and uphold you. I will not, I will not, I will not let you down. So that, being of good courage we are saying. The Lord is my helper. I will not fear. What shall man do to me?' "

See how God actually repeats Himself? That is so meaningful and beautiful to me. Why don't other translations render it that way? I have no idea. But I am not under the impression that all translators translate perfectly and precisely. I do appreciate that Wuest had a genuine desire to render a translation in English that was as close to the Greek as possible.