Meaning of the blank canvas (very last shot) *minor spoilers*

I just saw this movie and really enjoyed it although it was quite confusing and cryptic. Will give it another watch some time.

The very last shot of the movie was quite interesting I think: It shows a blank canvas for a second, then fades out. Interestingly enough I didn't find any discussion regarding this shot.

Idea 1: A blank canvas is the basis for any image and thus it contains all possible images. In the same way the imagery of the killer can be interpreted in different ways.

Idea 2: As the killer is dead, the art he created has now lost its meaning. The blank canvas symbolizes a new beginning for other artists (in the context of the film: killers).

Idea 3: The canvas is a symbol of death, which is ultimately the only human state that is open to interpretation.

Does anybody have any more ideas on what it could mean?
Thanks for your answers.