Everyone doesn't fear the Yonko. In fact, several of the Supernovas have attempted to and/or are planning on confronting them. Law just made a deal with Luffy to take down a Yonko, in addition to Luffy having to settle things with Big Mom soon, seeing as there is a bomb directly on it's way to her sent by him. And seeing as Kidd is also after Big Mom, the situation with her isn't gonna be that far off. There's no way Law will stick around for more then one saga, meaning the deal between them is gonna be dealt with soon.