Sorry, was on the road last week and every time forgot to reply to the thread. I don't think it's a secret, but I do feel uncomfortable talking specific numbers in public. I was aiming for 100 units, but that's not high enough.
It is partially because of Z170 being end of life and the LN2 board no longer being produced actively. So it would require setting things up at the factory again which in light of Z270 coming soon would be wasting manufacturing time I guess.