It's not impossible. If Nintendo can see the demand for something like the original Shadow Dragon NES release fully localized, Mother 3 isn't that far a stretch. I mean, fuck, we got Mother 1 as EarthBound Beginnings, even if that was an already localized but never officially released game.
Mother 3 is a different beast, the Magypsies would never fly these days. Nintendo would take a serious hit to their reputation for releasing a game with a humorous depiction of child molestation by a trans character, especially after what happened with Swapnote.