I live and work in a Chinese community in NYC. Most people here are aware and exercising caution, but there's no panic or run on masks. Many of my colleagues at work are planning to travel to Hong Kong, China, Malaysia, Taiwan, or South Korea for New Years, or for relatives to come here. I believe all three major airports, JFK, LaGuardia, and Newark are now scanning passengers inbound from China and other locations in Asia.
There's really no predicting what a virus will do. It can mutate rapidly to something lethal or fizzle out once it arrives in a population with a different germ pool. Example: The H1N1 influenza that killed off 3/4 of a village in Mexico did relatively little damage when it was carried from Mexico to NYC by high school students. A number of the students became sick, but only those who got sick in Mexico were hospitalized. The people who contracted the virus from the initial students got the flu, but in lesser virulence. To my knowledge, nobody died as a direct result of the students, although children, in particular, took a long time to fully recover.