I'm sorry to do this to you for the second time in a few days because normally I tend to see a lot of value in your posts, but wow, you're wide of the mark.
Archetypes exist because they develop as meta phenomena, arising from the structure of the story, not because they are deliberately written in according to a formula.
@Hela ninja'd me here but it really comes across as though you've read
about Campbell without really delving into the actual substance. Characters do not rigidly follow the HJ to the letter, nor is the author beholden to try, these questions arise after the fact and aren't somehow criteria for whether the story was "correct" according to some preexisting criteria. These things are not deliberately written into stories, they arise from the shared human experience of the author and the reader (viewer)
Luke famously followed
some version of the hero's journey in the OT, in fact he's often held up as an introductory example, Campbell 101, but as has been pointed out even there he diverges in several ways from being cast entirely in the mould, every hero does.
The OT has finished, however. Insofar as we view characters as being tied to an arc his is complete, but the real world doesn't work in story arcs, people live on after walking into the sunset. If he were to be included in the new films any actions he takes are moving beyond that arc, they are about what he does afterwards and real people don't act according to the sorts of structures you seem to feel should be imposed.
He
could be leading the resistance, he
could be training new Jedi, but he could equally have become a haberdasher with an interest in styling his hair, because that's much closer tot he behaviours real people demonstrate and frankly I don't want my fantasy to be constricted by the idea it
has to be a fairy tale, rater than being enjoyable for drawing on that.