Im actually thinking of making it take place in an abstract world where all the Shakespeares take place at one time. For example, Romeo and Juliet are the main characters, but Hamlet and Horatio make an appearance as well as some other people like Lysandar, Brutus and Puck. Im also thinking of slightly changing the ending of R+J. So, when Juliet is next to the "dead" Romeo, Romeo wakes back up before Juliet can kill herself, then Juliet suggests that they die together using some poison. Juliet drinks a "not actually poison" poison and gives Romeo the actual poison so he ends up paralyzed after which Juliet runs off. Romeo swears revenge and finds Juliet in a church. Romeo threatens her then Juliet explains that she is a Demon Hunter and cannot get Romeo involved because she doesn't want him to get hurt or killed from the demons. Romeo understands and suggests that they work together blah blah blah, kiss and make up and they're a Demon Hunting team now along with Mercutio as the "brains" if you will.
This might not make 100% sense to you, but I have it all figured out in my head, I just have trouble turning those abstract thoughts into sentences xD