There are many aspects of the play that would have to be different if the theatre director decided to give the roles to an all-female cast.
One of the main aspects that would change is that the fight for power would be less realistic. Although women enjoy equality in many areas of life nowadays, in the past, this was not the case. Therefore, a queen who governed on its own was unusual (though not impossible). Similarly, several women fighting for the crown in Shakespearean times is not a believable plot.
Another change that would be extremely important would be that of Lady Macbeth. Although the character is already a woman, and therefore, would be simple to keep her in the story, a lot of what makes Lady Macbeth a good character is because of the contrast with her husband. Her extreme ambition, cold-bloodedness and persuasive skills are unusual in the play, and attributed to her femininity. This would not work as well if there were no male characters to interact with her.
