Deuteronomy 18:20-22 strongly suggests that prophecy is that which will take place in the lifetime of the listener and prophet ... else, how could you put a prophet to death for speaking falsely. He's already dead.
Such punishments are unenforceable on "prophecies" that are fulfilled or unfulfilled centuries after the utterance.
Since CF couldn't parse the above reference:
20 But a prophet who presumes to speak in my name anything I have not commanded, or a prophet who speaks in the name of other gods, is to be put to death.”
21 You may say to yourselves, “How can we know when a message has not been spoken by the Lord?” 22 If what a prophet proclaims in the name of the Lord does not take place or come true, that is a message the Lord has not spoken. That prophet has spoken presumptuously, so do not be alarmed.
And, a prophet could always add, "well, not yet", to escape his punishment.