The Skeptics don't go far enough!! ... they should also declare to us another verse that "fails" in its prophecy.. in the exact same way, so to speak. (I speak as a fool).
(I argue below in italics, repeating their slight of hand to expose their error)
"Sure the failure of the Matthew prophecy is a good point, but consider an additional prophecy that fails in the same promise that some will "remain alive" until Christ comes again. Paul wrote to the saints and promised "We shall not all sleep (i.e. die), but we shall all be changed, in a moment, in the twinkling of an eye, at the last trump. (1 Cor. 15:51)"... That is another failure of prophecy! Its clear, Paul said some will remain alive until the coming of the Lord. Surely, no one who heard Jesus speak remains alive to this day, and to the same point, no one to whom Paul wrote remains alive to this day (i.e. all of them are asleep). The prophecies in Matthew and 1 Corinthians are both important verses that the Christian must admit.
The Christian has a dilemma. If Jesus did in fact already return during the life of those generations, to whom Jesus spoke and Paul wrote, then it was not very notable), or in the alternative, if Jesus yet has a magnificent return in the future, then it cannot be in the timing promised." ... so might say the skeptic..
In my humble opinion, the skeptic is the one who has the dilemma. The skeptic abuses the grammar, having wittingly or unwittingly "discovered" a prophecy that is not there. Jesus does not promise some will "remain alive" and Paul does not promise some will "remain alive". It simply is not there. Jesus speaks of a promised
death when He returns, and Paul speaks to a promised
life when Jesus returns. The proclamation of each passage has nothing to do with the timing of Christ's return deduced from the life of the listeners, but instead has everything to do with
what is certain, when Jesus does come. Both passages culminate with "what" happens, not "when" it happens. The premise that "timing" is the point of the passage makes for a lot of unsatisfactory explanations, and happy skeptics who divert the attention from the "what".
In 1 Cor. Paul declares the new life that the brethren will have when Christ comes, a life that we do not fully appreciate yet.. he said earlier, "Eye has not seen and ear has not heard". This promised hope of a new life, changed to incorruption and immortality, spurs the reader on, regardless of how long it takes to be fulfilled. "
Therefore, my beloved brethren, be ye stedfast, unmoveable, always abounding in the work of the Lord, forasmuch as ye know that your labour is not in vain in the Lord." The hope of the life to come spurs the Christian to labor.
So also Jesus, in Matthew 16, called His disciples to labor, to take up their cross, and to lose their life for His sake. He finished it off with a comparison to spur them on. He commanded his disciples to "take up their cross", to "lose their life for his sake".. to
die now, but promised that they who lose their life will find it. On the other hand, He acknowledged that some would refuse to take up their cross and die now. Some would try to save their life, but lose it. These would "not taste death till the Son of Man comes". The future death they taste at His return will be far worse than the death the disciples will experience when they take up their cross now.
In my humble opinion, Both passages constrain the Christian to labor with hope, because of what is promised to happen when He returns. Paul in Cor. 15 speaks of the resurrection and makes the application as an inducement to labor. Jesus in Matt. commands His disciples to take up their cross and die now, with the comparison that the death now is much less burdensome than the death to come for those who seek to save their life and refuse to taste death now. Neither passage speaks of timing.
Spurgeon did a helpful sermon on Matthew 16:28, and covers many of the common explanations.
http://www.spurgeongems.org/vols10-12/chs594.pdf