Yellow is badly squeezed, so most probably is going for slow growth, by just collecting cards and attacking small countries. Red and Black are in an ongoing conflict. Also Red has the upper hand in Africa, Black receives more as bonus, so all things being equal, in the long run Black has an advantage. However, Black may easily come under attack by Blue. So a treaty over Greenland for Black is a great diplomacy move. It also pushes Blue to focus on Red in South America which is even better for Black.
Playing as Red, he needs to finish the campaign in Africa. So this is exactly the opposite of previous case. Red needs to get a treaty with Blue so that Red can focus on Africa and also to get Blue to put pressure on Black from Greenland.
So far both Red and Black will benefit from Blue. But what does Blue want? What is in his best interest? As discussed many times before Blue can have a natural expansion to South America, so he can decide to go for Red. But that can be costly. Blue’s big fight with Red will make Black stronger every turn. So Blue doesn’t want any large conflicts either with Red or Black. Then there is Yellow floating around in Asia. Next card is set at 15, which is attractive. So Blue can simply grow and collect cards and expand in Asia waiting to eliminate Yellow when the right time comes. Meanwhile Blue can select Black or Red as the next target (depending on how things develop) after Yellow to make a chain elimination.
At this point in the game, Blue, Black and Red have many options and any of them can become a winner. Green and Yellow may need to wait to see the outcome of conflicts between the other three before they can have a go at it themselves.