"We are looking at some simple sentences. I am as good as the next in understanding subtleties in whatever language I read them."
Sure, I agree, they are simple sentences. But you're understanding them in a far too simplistic way. That's the problem. That, and the fact that you're wise in your own eyes. I'm sure you're a very intelligent person. But again, what you're not doing is hearing what what Matthew was really relating. That's why Mark's and Luke's accounts would be more appropriate for you, given your willful ignorance of the Jewish context of Matthew's account and his specific reference to Daniel 7..
"When Jesus was addressing his fish finders I strongly suspect they heard the meaning I took..."
I doubt it, given their silence. And...
"...it was given to instil faith and hope, which it did."
Here, I would have to ask what you think faith is. Faith is not a wish. And it is not "inspiration." Faith is a gift of God; Paul tells us that in Ephesians 2:8. And if God has given the gift of faith -- which was true of Jesus's disciples (followers) -- then you believe and understand things that you otherwise would not, because you would remain wise in your own eyes. And that seems to be the difference between you and me, by the way. So again, I feel certain they knew exactly what Jesus was telling them. Like me.
"Only when it became obvious that Christ's prediction was wrong did people search for 'subtleties' in the simple: 'I will come back before some of you are dead.'"
LOL! Jesus was not "wrong" in any way. In Matthew 16 (as well as Mark 9:1 and Luke 9), Jesus was saying, "Many you see here will be saved before they die."
"Angels may indeed frequent the high street. If they are such a commonplace, it's surprising Christ bothers to acknowledge them in his coming. If one can so easily see subtleties in the simplest of texts it is hardly surprising Christianity has many mansions, all differing and all claiming truth."
LOL! That's all I can say to this. LOL!

Well, except for a couple of things:
1.) Yes, it's unfortunate that there's so much misunderstanding or lack of real knowledge of many things Biblical, even among Christians. A lot of them have the same misunderstanding of this passage as you. But on the basics/essentials of the Gospel there is no dispute; there is perfect unity.
2.) By 'subtleties," I meant that really in the context of me and you (I assume you are not Jewish, and you obviously don't know the OT very well --specifically Daniel -- and thus can't read the NT in light of it. It's kind of like seeing a rainbow and only seeing the primary colors (red, yellow, and blue) and missing the secondary ones (indigo, orange, and green). Again, that's why Mark's and Luke's accounts of this same event would be easier for you to see and understand.
Mark's account: "Truly I say to you, there are some of those who are standing here who will not taste death until they see the kingdom of God after it has come with power.
Luke's account: "But I say to you truthfully, there are some of those standing here who will not taste death until they see the kingdom of God."
They understood exactly what Jesus was saying. And again, my guess is every single one of the disciples did, also.
Anyway, no, Jesus was really about as subtle as a freight train. Grace and peace to you in the Name of our (or at least my) Lord Jesus Christ.