Outside of Minnesota with the corpse of Conley, there’s no other hypothetically “good but could be great” (or better) team in need of a starting point guard.
So as good as Harden still is, his path is really: transition to the CP3 mentor role on a young or rebuilding team in need of a point guard, take the Russ role of being a super 6th man on a title team, or continue as is starting for a treadmill 1st round exit.