Alright, so it looks like Tabata resigned of his own volition, even before the earnings conference. Then Square cancelled the FFXV DLC's because they didn't want to do them without him as director, and then they wrote the cost of assets they had already developed for the 3 cancelled DLC's off as a $33m loss. So he didn't resign as a result of lost profit, but rather the lost profit is a result of him resigning. But the question is, why did he resign if Square didn't make him resign? It says he left for a new venture, but what venture could possibly be better than heading up a whole business division at Square Enix? Did he just decide that he can't handle the rigors of AAA development, so he left to head up a smaller AA or indie studio instead?
Maybe he just felt burnt out on Final Fantasy. He has been doing FF15 for how long now, it's been a fairly comprehensive project.