For the most part, I think we should trust people's instinct to secure resources for themselves in expectation of upcoming hard times. I live in Seattle. Due to the minimal testing that has occurred, we are just now learning of multiple cases which are being retroactively classified as Covid-19. These are from the very few that have actually been tested, which is a small proportion of those who showed severe enough symptoms to warrant testing.
Genomic analysis suggests that the virus has been spreading undetected in the community since January 15th
https://bedford.io/blog/ncov-cryptic-transmission/ This is from a virologist at Fred Hutch Cancer Institute who is part of a viral epidemiology study. If the virus doubles every 6 or 7 days as estimated, then... well, you're all good with your powers of 2, there are likely hundreds of cases already.
Every day there are new announcements of deaths from this disease just miles away, of new people showing symptoms, of people whose "flu" has been diagnosed after the fact as coronavirus. In a dense urban center like this with people crowded together on streets, in buses, in workplaces, I am working under the assumption that it is already in my neighborhood. I don't think that's unreasonable. The pharmacies in the area have been filling people's prescriptions for three months' worth without any prompting. They are planning for a long slog in which they want to keep people AWAY from the pharmacy as much as possible. The county has purchased a hotel to repurpose as a quarantine center, and is prepping portable isolation units. We've seen what a lackadaisical response brought Wuhan---it is not "hysteria" to work to avoid that same fate.
For the rest of the nation, I think it's eminently sensible to get a supply of nonperishible food, of prescriptions, of some fever reducer, etc. to last two weeks to a month. Get in the habit of washing your hands regularly, thoroughly according to CDC recommendations. Get in the habit of NOT TOUCHING YOUR FACE (it's very hard!) and all the usual stuff but actually applied. Be mindful of who in your family and community might be vulnerable, have respiratory conditions, be elderly, be in treatment for cancer, have an impaired immune system, etc., and make plans for how to protect them in the event of an outbreak in your community.
Those decrying "mass hysteria" do have a point---prudence can become paranoia, preparation can become panic. But mostly I think people should be encouraged rather than discouraged to prepare, because this will very likely be in your area soon.