I'd like to see a source for "It is already economically viable...". Maybe at current levels of production, but you can't just assume current levels of output in every sector while removing incentives.
I'm not talking about a beachfront mansion and a Ferrari in the driveway for everyone. I'm talking about not starving. Want to be more than the bare minimum? Then choose to work. Don't care? Then don't work - not that people who don't care are effective employees anyway.
You're really stupid.
Arguments about how expensive things are make no sense if we restructure our society where money is only half the equation. The labor required to provide food, health, and housing is incredibly small compared to the overall economy.
People want to be useful, and people want more than just a place to live and food to eat.
The real danger would be in creating a system that stifles the free market side of the economy and leaves people stuck in basic assistance hell with no way of working to improve their lives. Worrying about the costs of providing basic assistance to all is actually the least important bit.