Your thread title is split into two parts:
1.) No, the current Apple Pencil will not work on the iPhone.
2.) I don't see Apple adding any Apple Pencil functionality to the iPhone. It's not something they likely will venture on, because the Apple Pencil is intended for the iPad Pro line primarily for sketching/drawing/editing and it's gives the iPad Pro line more exclusivity.
Being as large as the Apple Pencil is, I see it primarily being used for larger display with the iPad. If Apple were ever to implement an Apple Pencil to the iPhone, I would imagine they would make it smaller, more compact to complement a smaller display.