Dhchristian I am pretty certain the 7th head is representative of the Holy Roman Empire. When we look at the statue from Nebuchadnezzar's dream the head of gold is Babylon, the arms of chest of silver was Medio-Persia, the belly and thighs of brass was Greece, the legs of iron was Rome. Now the feet of iron mingled with clay, you keep the iron aspect but add in clay or a religious element to it signifying the Holy Roman Empire.
Now the 7 heads are as follows the Egyptian Empire, the Assyrian Empire, the Babylonian Empire, the Medio-Persian Empire, the Greecian Empire, the Roman Empire, then last the Holy Roman Empire. Now it tells us that the 8th is of the 7 so that tells us that one of those empires will be reborn. That empire will be the Holy Roman Empire reborn which has already happened, we call it the European Union.