Instead of being in Brothers now since the introduction of the new red weapons and other gold/old red weapons being available in early TIs, most likely it will appear there.

I wouldn't know since I have no need to do any other TIs beside Brothers and Pain hard. However, the last time I needed to do the akatsuki Ti (especially normal and hard), they dropped frequently but this was back in 2.0 so I don't know if it changed in 4.0.