I have long thought, ever since I was a child, that the seven mountains might not mean what WTBTS says it means, but that it may mean seven continents or seven seas instead.
And therein lies the beauty of myth.
Myth is a template that can be experienced at any time and place in history. Myth weaves itself into the fabric of human existence and functions as the thread that holds time together.
The seven mountains, seven kings...whatever metaphorical device that the myth has been placed within...can mean whatever you choose it to mean. The value of myth is finding your place within it.
Here is an example - at one time, Russia was guarded on her borders by seven Cossack clans. These clans were called "the seven pearls of Russia". Why can not the seven mountains be interpreted as the seven Cossack clans in that point in history?
Of course the meaning/view of myth changes throughout time - pick an interpretation that fits your life and go with it...myth is meant to be flexible.