Danny may offer Michelle an annulment once he's sure she's safe, but he's not going to give her one now. It's too risky. So, what will Danny offer to Michelle? My guess is that he's going to make her a player by giving her half of everything he owns, and that will include a hefty chunk of the Santos' only legitimately run business.
What if Carmen gave Danny one of the family businesses as a graduation present? Danny gives Michelle the lion's share of his business, she wills it to Rick if she dies, and Carmen's hands are tied. Danny might even promise Michelle an annullment as well, but before he can follow through on it Carmen fights back with Ben, and she winds up taking Manny to court to keep the business in the family. That way Manny could spend the next few months at the Bauers battling Carmen while growing closer.
Like I said in the beginning though, this is just a guess, and it's coming from a someone who sees no need for a Messe reunion so it may just be wishful thinking on my part.
This might also explain the current twist in Manny's storyline with Michelle betraying Danny, and Danny sleeping with Drew. If Manny will be at the Bauers (a safe, loving environment) working together, and growing closer, then they'll need internal conflicts to keep them apart, and now both will have them.
Rhonda