I realize this is an old thread but wanted to comment. Was thinking that the 10 horns and 7 powers could be this. The great world powers.
1. Egypt
2. Assyria
3. Babylon
4. Medo-Persian (two horns)
5. Greece
6.Roman Empire
7. Dual British-American world power (two horns)
8. United Nations..Springs out of the 7th power
Here we have ten horns and seven powers...U.N. springs out of the 7th