Do you know Blake personally? Doubtful. I'm sorry, but I hardly think it's fair to insinuate that he is an alcoholic (yes, your comment about staying sober suggests that). It is also unfair to suggest that the "clique" will implode. By all accounts, those in the "clique" all seem to actually enjoy each other's friendship. Yes, Blake says things that rub people the wrong way, but I don't know what that has to do with him officiating a wedding of his two friends. Keep in mind that Kelly and Brandon know Blake as a person, not Blake the celebrity. By all accounts, Blake is actually a really nice guy. I haven't heard many celebs or industry people speak badly of his personality. Actually, several people have made statements about him being very giving and sweet.
Again, you are making an awful lot of assumations based on public image and not actually truly knowing the people involved.