My understanding at this point is that you can take the formations and they count as detachments, no? Granted you don't get the Command Benefit from the CAD/AD or the Eldar Warhost Command Benefit, but you don't have to take all the Warhost pre-req's either?
This would be a legal battle-forged army? So if you want to play Iyanden, you would use the Wraithhost formations and just get no "Command Benefits"?