I think that at the end of the series the twins find their parents or other relatives and leave Nod's Limbs with them, Edgar and Imogen get together (some of Edgar's lines in the last book made me think he likes her) and he eventually joins the circus and Ellen may or may not follow him.
Heimertz, Madame Dahlia make amends with their family, they (and Pet) return to the circus and maybe Heimertz and Dahlia have kids (twins hopefully n_n)
Miles stays with his parents until he's old enough and follows the twins or is adopted by Edgar and Ellen's family.
I have a feeling that Nod will die in the next book (don't get me wrong, I'm a Nod fan myself and I did hate it if he died but for some reason I can see it coming).
Stephanie will either die or be sent to jail/an asylum for life.
Or maybe the twins' parents as also after the Balm and/or the Ithunes and don't care about the twins so they either stay with Nod (if he lives). Since Nod died the twins decide to go back to living alone in Nod's Limbs but the Heimertzes convince/force them to join the circus and the Midway Irregulars (I can see Ellen being the defacto second-in-command). I like this ending better.
What do you think?