It seems to me that your suggestions turn Beliefs into ‘quests’ rather than what they are supposed to be, which is…beliefs. They are things the character cares about and believes in. They should include a value statement followed by an actionable element. To adjust your example, it should include one more element:

“My kingdom will prosper if we are able to trade with the Eastern Kingdom. I will travel there myself and discover what might open those doors.”

This leaves room for your belief to be properly challenged. Now the GM could introduce a character or evidence to suggest that your kingdom will NOT prosper if the Eastern Kingdoms open trade. Perhaps a local artisan who explains how his family business will be ruined if you allow cheap imports of goods from the Eastern Kingdom.

I think the value statement performs the same job as the ‘long term’ statement you were describing in this post, but it makes it more of a belief rather than a quest.