I kind of hope we get two narrators. One to do the male roles & another to do the female ones. This is a multi narrative book, and it switches between male & female roles enough that it would help to have a dedicated male & female reader.
While male & female narrators can alter their pitch to do a passable representation of the alternate gender, it is hard to pull off. Especially for multiple male & female roles like the book has.
BTW; Yes, I've read the book. You could get one at SDCC if you followed the @acerocbooks Twitter. I will likely review this weekend, as I have just finished it, but this is where my knowledge comes from.
Looking through the book, there are 6 different voices in total. Male & female voices are a roughly equal, if you include the cat. If you just count humans, there are more female voices. So we likely will be looking at a female narrator. If that's the case, I really would like Tara Strong if at all possible.