A Mandalore book? Unlikely. We will probably see bits of Madalorian content here and there. Equipment, armour, weapons, vehicles, etc. Maybe a species as we have Correlian. The upcoming Bounty Hunter book or an AoR Imperial version of Strongholds (Bastions of Oppression) are good places for information.
If that's gonna be the case I'm cool with it. Though I'd really like to see FFGs treatment of the Mando culture. They did a darn fine job with the corellian one.