Death happens even slower than testing. I personally estimate that the death rate will be something like 0.5-1.5%. South Korea has done the most extensive testing, and they currently have a death rate of around 1%, but of course even they can't guarantee they've found every single person with Coronavirus (and some of the people they found may still die).
The problem is that if we don't do quarantines, we will end up in a situation where we depend on herd immunity to stop the virus. Herd immunity starts happening somewhere at 40%-60% infections. US population is 327 million, so let's say 40% is 130 million people and 60% is 195 million. That's a lot of people to infect and a lot of people to die.