There are different stories about how John met his end. I incline to the one that says he was martyred. The passage doesn't actually say John would never die.
John 21:22 Jesus saith unto him, If I will that he tarry till I come, what is that to thee? follow thou me.
23 Then went this saying abroad among the brethren, that that disciple should not die: yet Jesus said not unto him, He shall not die; but, If I will that he tarry till I come, what is that to thee?
Too many possibilities in that verse to use it to confirm the physical end of him one way or the other... without a definite revelation on it, which I have not had. Oh, I have received a message through it, but it has not to do with his physical death. It does mean that we should not be so concerned about the other guy when it is not really our business to look to deeply into God's will for him. But... what does it mean to me and God's will for my own end?
Each of us should have a purpose in God's plan if we are able to see it. Many of those who do not have such a vision don't want to... Others perhaps who have a vision have chosen to ignore it in favor of their own established plans... even in the what they consider the Way of God. This is a way to that delusion from God that comes with a lack or loss of love for truth.
Rather than being "caught up" I believe he responded to the words, "come up hither" Rev 4:1. This was a revelation given to John, but I am not so certain that it was the end of his course here as a man of flesh.I think he did tarry until Jesus came for him; and we have a record of it in Revelation. One part went up forever to be with the Lord, while another part remained on earth. Didn't John hear a trumpet and get caught up in the air?
As to Jesus coming for him... in a sense Jesus comes, or has come, for each of us. It could like with the 10 virgins of whom only 5 had filled lamps.