Yep, I would have agreed with you up until recently. But we have always thought, that could never happen here.
Of course we probably always thought we could never elect an outright Marxist to the Office of President either.
The old Commie trick used to be three steps forward and one step back.
Now we came no pretense of going back, it is just two steps forward, then hold until people go back to sleep and restart the process.
We eventually will have a Progressive that will attempt to solve what they perceive as a threat to their world, 8 billion people (not a part of their world by the way) is that threat. You guess how they might address that threat. In the past nature gave a hand, or wars but those are not all that dependable, so ultimately they will decide. Old people are the most expensive to maintain, so they would be an obvious first target.
A flu vaccine could be made that would likely be more fatal to the old and infirm, and could even get a few unhealthy young people, not unlike a natural infection.
If you think this is impossible then you haven’t evolved your thought process to include the unthinkable, because I am very sure many in the current government have.
Who in the opposition party would you bet your life, on them telling you the truth?
Tin foil, it is not just for the kooks any more.
Much more likely is a move to ration care after a given age or an arbitrary quality of life scale.
Most likely, though is a drift in public opinion http://lifeethics.wordpress.com/2007/01/24/uk-survey-doctors-should-probably-kill-patients-2/ and http://wingright.org/2011/08/24/murder-and-medical-ethics-viewpoint/
This would follow a move toward the public health policy of the Netherlands, where one in 10 die due to intentional - not always voluntary - euthanasia.
About 1/3 to 1/2 of doctors and the general public support killing by physicians - so called “physician assisted suicide.”
If I were to look for conspirators, I’d start with all the people with degrees in Public Health and the extreme objectivism of Randian utilitarians.