Not as an expansion pack. No. I'm not paying 400 kr for my occults to pair up and produce hybrid children that are stable and not glitched up. This is much more of a cross-pack compatibility thing.
Which, don't get me wrong, I would absolutely love to have. Mixed-occult pairs already exist in countless people's games. Occults have been abducted by aliens, which happened in my game once - it produced a glitched alien-vampire hybrid. Her forms are a mess and bringing her into CAS is risky business.
Sims 2 had occult hybrids. Sims 3 refused to do them, but I guess there's a good NRAAS mod for them.