I think I've figured out how the extraction machine works in Continuum. It uses an itty bitty version of Asguard beaming technology (the different coloring of the beam means that they've done something to it to cause it to act as a sedative too) in order to preserve the Host's life since the surgical extraction has too good a chance of killing both Host and Symbiot (in case they want to interrogate any remaining Gou'ald). And the liquid when the vial was smashed was spinal fluid or some other liquid that surrounds the symbiot to help keep it cozy.
But this is why they were able to get it out of Ba'al as they did.
Daniel doesn't die. Cam is able to get him through the gate after Sam is killed. So both he and Daniel end up in the past together. Daniel has to abandon his prosthetic leg because of its too modern.
If people ask they claim to be brothers and Daniel was injured during WWI, Cam uses one of his Great-Uncles as a template when people ask where Daniel served. When it comes time to stop Ba'al, Cam leaves Daniel in Boston (they've set up a support system to help Daniel out for while Cam is gone) and goes to Alexandria and stows away on the Achilles.
When the boat arrives back in Boston, Daniel is at the docks to greet him. While Cam has been taking care of business, Daniel has also been seeing to getting them some land in an area they know won't become too populated in the future and put a house on it (Cam probably builds their small home on it himself to keep their interactions with others to a minimum).
This entire thing can be slashy or not. Either way would be really cool. And I so am not writing it. If anyone wants to write it, you have my blessing.