Clarke's Commentary on the Bible
There be some - which shall not taste of death - This verse seems to confirm the above explanation, as our Lord evidently speaks of the establishment of the Christian Church after the day of pentecost, and its final triumph after the destruction of the Jewish polity; as if he had said, "Some of you, my disciples, shall continue to live until these things take place." The destruction of Jerusalem, and the Jewish economy, which our Lord here predicts, took place about forty-three years after this: and some of the persons now with him doubtless survived that period, and witnessed the extension of the Messiah's kingdom; and our Lord told them these things before, that when they came to pass they might be confirmed in the faith, and expect an exact fulfillment of all the other promises and prophecies which concerned the extension and support of the kingdom of Christ.
To his kingdom, or in his kingdom. Instead of βασιλεια, kingdom, four MSS., later Syriac, Coptic, Ethiopic, Saxon, and one copy of the Itala, with several of the primitive fathers, read δοξη, glory: and to this is added, του πατρος αυτου, of his Father, by three MSS. and the versions mentioned before. This makes the passage a little more conformable to the passage already quoted from Daniel; and it must appear, very clearly, that the whole passage speaks not of a future judgment, but of the destruction of the Jewish polity, and the glorious spread of Christianity in the earth, by the preaching of Christ crucified by the apostles and their immediate successors in the Christian Church.