''No, I just contextualised in another aspect. Heaven and earth will pass away, but my words will never pass away.''
That is indeed what you do. When this technique is used to rationalize inconvenient truths, in this instance verses in the bible, it becomes an example of equivocation.
Once again, the witnesses/listeners to the described event of the return of Jesus in great power and glory for all the tribes on earth to see are told that some would be alive to see it happen. Simple as that. Undeniable. Which is exactly what the first Christians believed. Then because the prophesy failed came the need to keep pushing the event further and further into the future....and here we are, two thousand years later.