I was thinking about that too. Id rather not have her if she is just another cash-syphoning expensive cameo. Theron can act when she puts her mind to it. Either it was the script (most likely) or her performance, but she was a waste of space in Prometheus. That role could have been sooo much more and could have easily eclipsed David's. Id rather not have her back unless she has a meaningful role and puts her acting chops behind it. Not that I have a choice anyway...
(Im not against Theron, but her role needs to add deep rooted non-superficial value, not just be thrown in there as a tacky cameo)