This kind of vision about the times was clearly implied in the language of Ruhollah Khomeini when he was calling for a movement against the Shah in 1979. And Khomeini himself was sometimes spoken of (especially by his students) as "the Imam", a term that in that context vaguely implied that he was the long awaited Mahdi/12th Imam. The ambiguity was deliberate.
Khamenei's speech is a sign of a serious attempt to muster the Iranian people for a sacrificial war comparable to that Iran was forced to fight the army of Saddam Hussein in the 1980s. So it is reason to worry. Iran is being seriously boxed in, and so the regime could take measures that could lead the country and the region into war.
What I wonder is how this rhetoric can sell in today's Iran. Khameini well knows how unpopular he and his clerical administration is. He is not crazy, and this administration is much more savvy than we sometimes take them to be.
We can all regard the many signs of instability and hatred in the world, of which this is one, as reason to hope that the world leaders will demonstrate restraint and wisdom.