I don't know how they could be retrieved successfully since the US Navy DSRV crush depth is only 5,000 feet; the only hope they have if they're still alive, is to get the propulsion back so they can maneuver to a more shallow depth.
So sad.
I don't think anyone can actually take the company to court, the passengers signed their lives away (pardon the pun), to be able to take that ride to the Titanic.
I would be curious to know if it had a backup propulsion system in case the primary failed?