From Adam Clarkes Commentairies on the Bible:
Mat 16:28 -
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."