Maybe the national guard or whatever would start distributing rations or something. It could get bad, but probably not post apoc movie bad.
I think the max is half as bad as a post apoc movie. Parts of the US could look like Katrina, the rest would be puckering their butts and hoping they still have jobs.
If we shut off all traffic with china (which may happen) two things could happen.
1. Stock market dip as panicked people pull their money out.
2. american businesses would be pretty damn screwed, which would lead to job loss over the next six months.
Even some of the burger flippers in this thread might be out of a job if the paper bags mcdonalds buys from china can't be easily bought somewhere else.
Now compound all of that with the sick people missing work, and other people dodging work, and you can see how this shit all goes real bad real quick.
1. Stock market dip (probably worse than 2008, maybe as bad as great depression)
2. Supply chain completely fucked because our businesses rely on china.
3. People unable to work, or refusing to work. Business also not seeing customers as everyone hunkers down. They start laying people off to not go belly up.
4. Rent, mortages, credit cads, and other loans not being paid because people missed work, their jobs shut down, they were fired, or the voluntarily quarantined themselves to keep from getting sick.
5. Market sees 3 &4 and gets worse.
6. Supply chain further affected by 3, 4 and 5. Food isn't being distributed around like it use to (grocery stores empty).
7. People start getting hungry, looting starts, police are either sick or overworked.
While its highly unlikely I could see martial law being declared in quite a few places. Then the riots will start, and the killing begins. At about 3 you want to get the fuck out of any large town or major city. If you don't, or can't then my prayers are with you.
Everything above is moot if the virus turns out to not be a big deal though.