¿Tetralogía?

Pues sí, parece que Jonathan Demme no está cansado de hacer películas sobre Neil Young, y no ve como trilogía lo que ha hecho hasta ahora, sugiere en esta entrevista que puede haber más:

It's the third piece we've done together and I guess the physics of threes, certainly in film or in books, you become an instant trilogy whether you like it or not. And if you've joked a little bit because you want to do another one after you've done, then you're stuck with the whole trilogy thing. But this is a stand-alone piece and I hope that we will turn it into a quadrilogy as soon as possible.