"'"But the court will sit, and his power will be taken away and completely destroyed forever. Then the sovereignty, power and greatness of the kingdoms under the whole heaven will be handed over to the saints, the people of the Most High. His kingdom will be an everlasting kingdom, and all rulers will worship and obey him."'" NIV translation
At the end of this tribulation, Satan and his followers are put on trial and stripped of their power. They are cast into hell and the saints will possess all of the earth.
"'This is the end of the matter. I, Daniel, was deeply troubled by my thoughts and my face turned pale, but I kept the matter to myself.'" NIV translation
Daniel knew the future but it was scary to him and he kept it all to himself for a time.