Because Babylon is a system, we cannot physically flee it. We have to flee by keeping our minds clean from the customs, traditions, and cultural influences.
The circumstances surrounding Nebuchadnezzar's dream set the stage for God's revelation of His power, plan, and prophetic intentions (through His servants).
Daniel 7-8 is full of overlapping images and visions. Both chapters show the certainty of the end of Gentile kingdoms, replaced by God's eternal Kingdom.
Because all things will be violently shaken, God commands His people to place their trust in the unshakeable Kingdom of God which will displace all empires.