Someone may have already asked this, but who would come out ahead if every kingdom tried to implement your Economic Development Plans more or less at the same time? Is it just a case of the-rich-get-richer where the Reach and the Westerlands ride their advantages to economic supremacy, or do the poorer kingdoms (the North, Dorne, the Stormlands) have some hope of catching up?

Discussed somewhat here and here. 

It’s not just the case that the rich-get-richer; economic development can rapidly shift who’s rich and who’s not both inter- and intra-regionally: look at how England shifted from a relatively poor nation into the economic and financial powerhouse of Europe due to the commercial and industrial revolutions, or how the economic balance of power within the U.S has shifted over time (the Industrial Belt becomes the Rust Belt, the South moves from the “Nation’s #1 economic problem” to the Sunbelt, the factory towns of New England that have become hollowed out when the factories moved away). 

My thinking is that the winners and losers have a lot to do with two main factors: timing and advantage:

• When it comes to commercial infrastructure, getting there first gives a given region a huge head-start over their rivals, as was seen historically with the Erie Canal putting New York ahead of Pennsylvania and Virginia when it came to capturing the new east-west trade with the Midwest. 
• It also matters, on an industry-by-industry basis, whether a given region has an absolute or comparative advantage in that industry. So for example, the North is going to be very difficult to beat in the wool and woolen garment trade once it captures the higher valued-added segments of the industry, because it has such a large amount of land that’s suited to pasturage. Yes, the Reach is large, but you’d be giving up a lot of agricultural productivity by shifting over from cereal crops, fruits and veg, and dairy farming to sheep, so that raises the opportunity cost of investing in that industry. (On the other hand, the Reach might have lower opportunity costs when it came to linens or cotton.) Likewise, the Westerlands are probably going to be hard to beat when it comes to finance or metallurgy.