Days Spoilers Jan 13-17

I wouldn't be surprised if she doesn't turn out to be not dead later, but like glo said, I think this is just a fantasy sequence of Will picturing Adrienne - like the hallucinations Jen had when Jack was supposedly dead.

I think the suspicion that somehow either Maggie or Sarah were responsible, accidentally, for Adrienne's death, has a reasonable amount of plausibility; especially given their response during Monday's episode.  It's arguably the thing that makes the most amount of sense for why Victor and Xander would be not only willing to let Will be falsely imprisoned, but adamant Ciara not say anything.
The only other one that comes to mind would be Sonny, which could actually be an interesting twist.  Because he would definitely be someone that Victor would be willing to protect on the same level as Maggie certainly; and especially given the tragic nature of being responsible for his own mother's death, that would be something Victor would want to cover up given the chance.  It could even turn out that Will knows the truth, but would willingly accept the burden of letting Sonny think it was Will rather than know it he was responsible for his mother's death. 

It would also certainly simplify things since a scenario where either Maggie or Sarah were responsible would require this cluster fuck of circumstances, where Will, Adrienne and Sarah/Maggie were all present, in order for Will to be as plausible as the guilty party as either Sarah or Maggie.  But if it were Sonny, not only does make sense for Sonny and Will to be together when whatever happened went down, putting Adrienne with Will and Sonny would be a much more natural to come by circumstance; than to have a bunch of different people happening to to converge on each other.
But at the same time, it being Maggie or especially Sarah, would certainly be a more motivating factor for Xander, but seeing as how being made CEO was his pay off for his involvement in the cover-up, I'm not sure he did it strictly for altruistic reasons.

What I really don't want is for them to play it off as part of a baby switch, like has been suggested - where it's this whole big thing of Adrienne dying, Sarah and Kristen both go into labor and Sarah's baby is the one who actually died through whatever circumstances also killed Adrienne.  That would just be too fucking convoluted.  Never mind that I don't want Kristen and Brady to have a child together; that'd just be weird.