Almost all of your Westeros Economic plans suggest creating regional banks, but there’s a bit of a snare I don’t think you’ve gotten around: How do you topple The Iron Bank’s monopoly, or at least protect the new banks from reprisal from the Iron Bank (e.g. The Rogare Bank) once they begin attracting attention from across The Narrow Sea?

Well, the Iron Bank doesn’t try to destroy every other bank – after all, there are a number of other organizations that are lending money in large amounts in other nations (and indeed, the Iron Bank probably does a lot of business with other banks). Rather, they act against banks that rival their power. 

But even then, the Iron Bank isn’t omnipotent. Dealing with the Rogare was a lot easier than dealing with a Westerosi bank would be, especially one with the explicit backing of a Great House, due to distance and the internal politics of the Free Cities. A Lannister Bank, for example, would be difficult to deal with, as Tywin’s hegemony within the Westerlands would make it difficult for the bank to find rebels to finance.