When you speak, cough, sneeze, or breath you release water droplets into the air. Large droplets fall to surfaces within 1 meter quickly. Smaller droplets may stay suspended in the air for a longer amount of time and travel over 1 meter, but they too will eventually settle on a surface. This is why social distancing is important. However, the droplets coating surfaces is of larger concern since it can live on surfaces for several hours to several days. Most people touch their face between 16-23 times an hour from the studies I've seen. If you touch a surface that's been exposed and become infected, it's possible for you to spread it for days or weeks without showing symptoms yourself.
My understanding is if too many people become infected and need serious care our country doesn't currently possess the equipment, space, or personnel to adequately provide. Hospitals are already becoming overrun, running out of supplies, people are dying in ERs waiting for beds, and in New York they've had to park refrigerated trucks outside to hold bodies. Once health care professionals start getting sick because of lack of masks, gloves, etc then the system will start to collapse and even more people will die from lack of care. So we're social distancing to try to prevent that from happening.
I don't think this is the end of the world, but I do believe it will spark a wave of ingenuity to combat further instances. Since this seems to happen every decade or two and seems to be getting progressively worse. I'd imagine more factories will be considering automation for example.