@Germanico described CoN as "a PvP operational war game" earlier today. I don't think it's an operational war game if you can win it through economic means without fighting other countries. Phrased differently, (imho) no such condition exists.

In my experience, Trade Embargoes have primarily been a tool of the AI to serve as a punishment for players who apply strategic bombardment doctrines against "populated" areas too often. In the hands of players, Embargoes are primarily a method by which to express displeasure with another player without straight-up declaring war and taking the morale penalty; with the exception being: Players who actually make an active and effective effort of playing the market, and even then, the effect is really only noticeable in the early game if there are few AI countries left and few players buying or selling; or in the late game where there's a handful of people with massive resource pools that are just doing it for grins or to fill a deficiency.

My opinion is that, in essence, the only consistently effective method of economic warfare is by way of Corruption and Sabotage agents, applied in large numbers against major industrial centers and targeting only one or two specific resources. And even then, spies are expensive enough that, without supplementary cash injections from allies, or an exclusive focus on trade and your money pool, this method isn't particularly viable in the early or mid game without being landlocked on all sides by trusted allies that support your efforts and are willing to compensate for your absence of substantial military defenses with their own troops.

In short, as Rasczak has pointed out: Conflict of Nations, like Call of War and Supremacy 1914 before it, is primarily an operational war game, with players fighting with simulated soldiers and weapons. Economic warfare isn't really intended to be a go-to means of waging war barring role-playing rounds between individuals looking to create a story.

I feel that there should be some kind of more effect of the trade embargo. It right now does not really affect you when someone puts it on. One way it could change is if they made countries more dependent on the trade system, but that is not very reliable, there have been many games in which I have seen a global lack of resources, ei most people are missing components and no one is selling. So unless something with that is changed basing ones economy wouldn't work. Since most countries are basically self sufficient the trade embargo basically does nothing. Maybe it could be tweaked to maybe hurt morale some, affect your normal income a little, or even possibly slow research down. Im not sure if those would help that much either though. With how the economy works in this game it doesn't really mix well with trade embargos. If we had it where you have some countries are good at producing one type of resources (ei Venezuela and oil,) but needing to buy something else as well, (ei, Venezuela and needing to import food and Medical supplies) then it would help some by having certain countries strategically embargo, (ei major oil nations embargoing a country that lacks in oil production). This would need some kind of more advanced economy. But one part of the Economy that I Know for sure won't be changed is resource trading, devs have straight up said thats never coming back, so that can't be a solution.