He said, "Behold, I will make known to you what shall be at the latter end of the indignation, for it refers to the appointed time of the end."
Daniel's visions of the empires of the Middle East just keep coming from the Lord in this book. And the visions get stranger and stranger with each new one. The vision of the ram and the goat is at first almost cartoonish in its imagery, until the deadly serious nature of it subject matter and meaning starts to emerge in its explanation.
The ram has one horn longer than the other and represents the Median/Persian empires that Daniel helped administer. This empire would be toppled by the swift single-horned goat that ran so fast its feet did not touch the ground (the empire of Alexander the Great from Greece). That empire would topple Persia, but at a price. Alexander died and his empire was divided among four of his generals. One empire would control Jerusalem... the Seleucids. This is where the vision focuses its attention. From that empire would arise a ruler who would dramatically persecute the Jews and who would desecrate the temple and threaten to wipe out the worship of the Lord.
These interpretations do not however explain Gabriel's caveat in verse nineteen. He makes it none to Daniel that what is being revealed has to do with "the appointed time of the end." This is much more serious than just the Persians, Greeks, or Seleucid rulers playing out their game of thrones. There is more fulfillment then in this passage yet to come, and that is why Daniel is instructed to "seal up the vision" in Daniel 8:26. This has to do with what God has in mind as human history unrolls to its end. And in that sense it has a deeper impact and requires very careful examination and understanding of the biblical texts that specialize in prophecy.
I am not at all an "end times" expert. I do however have enough respect for the authority of the plain reading of God's Word to trust that this passage informs a yet final set of future events. And I will respect it as such. Any hermeneutic that limits it only to the events of the Persian or Greek empires is choosing to disregard the clear claims of the text. I would reject any such interpretation in favor of one that respects what the passage simply claims for itself.