I think some of us are giving him too much credit, what with elaborate plans and right to die drugs and all that. I think when all is said and done, it will be simple: he no longer wanted her around, but wanted the baby, but didn't want to pay child support to her or deal with her in general. So he thought, well I'll get rid of her, and get someone to do it, and what do you know? Thanksgiving - I'll be with family so they'll all be my alibi that I wasn't around when she vanished.
Except to get Baby K, he had to place himself at the home anyway, and I think he just wanted to get it done and over with, and took care of it himself. Perhaps the person he solicited has finally come forward and told what they know, and that's why their physical safety is important. PF is behind bars, but his family/friends/supporters aren't. In this situation, he is the only one responsible, the other person is not culpable, and the solicitation charge will stick as it.
In an alternate scenario, he came and took the baby, someone else came after and committed the crime and cleanup. Thus he thought he was home free and hence his smug demeanor. Maybe this person is now cooperating, and the solicitation charge will be dropped for a conspiracy charged if/when the person is charged with murder. I find this to be the less likely scenario though, as I just don't believe the actual murderer would not have been charged yet.
Ultimately, my opinion is that he asked someone and took a step towards it (solicitation), but the person did not go through with it, so he did it himself. He cleaned it up. Maybe in the bathroom. That's why a cursory search would not have yielded anything. Maybe search #2 involved luminol and taking apart the shower drain. Any significant amount of blood, or brain matter/tissue, would lead them to conclude she is no longer alive.
Bottom line, he's going down. Not a chance in hell he's going to get away with this, body or no body.