And furthermore there should be a feature soon allowing sharing cards with other players for a time. (Or renting them out apparently.)

That will make everyone in a guild more competitive. (Not everyone plays all the time, meanwhile other players can use this or that card.) Then they all can get high rank? And maximize free cards in that case.

Out-of-game coalitions, like in game theory.

The whole game is excellent for experimental economics because of the blockchain element.