I like it. I was actually going to ask if you wanted to do Wraith's whole underworld society thing, since it feels like the different worlds were always a weakness of Wraith ... as you say, it loses the point of playing a ghost.
It should work. I mean, think about the PC-NPC-PC triangles idea. You're going with the idea that someone's connections to the world of the living ('chains' was the word you were using earlier) have a definite effect of some kind on their ghost, like with fetters in Wraith? Sounds like the GM wants to tie together characters' chains. Sure, it means that most of the game's focus will be on interactions with the living world, but hey - point of playing a ghost, right?
You'll also be able to create ghost-ghost relationships in the same way you would in anything like AW classic. Maybe that Pardoner over there needs help collecting on a debt. Maybe a couple of Poltergeists have staked out a neighborhood as their haunt, and they're trying to drive you or a friend out of the area. Normal stuff. (It occurs to me that, in the absence of mortal law, a ghost game could have a lot of the same issues of a post-apocalyptic game.)
Is it the Pardoner you're worried about? If you re-flavor it a bit, you could broaden their abilities beyond just manipulating Shadows to also give them the ability to fiddle with chains. Similar concept, and they're still not directly interacting with the world, but now there's an obvious reason that someone might involve a Pardoner in their world-of-the-living issues.
I'd maybe consider dropping the, um ... the playbook that was about manifesting in the world. The Apparition? If it's to be a game about transitioning out of life, dealing with your chains, and etc, then that playbook might be better served by breaking it and giving the bits to other playbooks. That way, a character can manifest in the world in his book-specific way, but nobody is super-good at it. It ought to be difficult to, say, talk to your daughter.
I think Orpheus did something like that ... like each ghost splat had a 'when you manifest, you can be perceived like this, and you can do these things' section.