"""""I don't see why Padan Fain couldn't become some sort of god. It's hardly new to mythology. The power of Shadar Logoth was so immense that the whole White Tower was said to not be able to contest it, which was pretty much proven by the Cleansing. It's possible that the Dark One is like Morgoth from LOTR, and that Fain could become another form of great evil like Ungoliant."""""



If my memory serve. RJ says that both entities are equal in power.

As for Fain taking the DO place. Well In terms of power, I see Fain as strong as Sauron, wich is by far the strongest being in LOTR 3rd age. But Still a pale shadow of Morgoth.

Even If all the white tower combine can't destroyed Mashabar (but a really small part of the DO power did), they can't destroy the DO as well. It is not because you can't climb the Kilimanjaro that it means, it is as hight as the Evrest.