Apple could add a passive eraser to the end, and have the screen detect it. All it would take is the addition of a capacitive capable rubber (same material as the Apple pencil tip), or perhaps plastic coated with rubber (to protect the lightning connector). It could be a small separate add-on that I'm sure many artists would appreciate, and not mind purchasing separately.
There's a lot of tech in that screen ... it's already capable.
Considering the screen already has fine-tuned surface point detection, no matter how an artist erases, the shape and size of an eraser makes it a different contact space (whether the artist uses the end, side, or a corner of the eraser). They can differentiate between a pencil tip and an eraser purely in a software update. A passive eraser would suffice, if the artist wants fine levels of pressure to for erasing, they can use the pencil tip as designed.