1. There are more infections out there than are being reported. The numbers out of China are pretty much garbage, both due to political reasons and testing limitations. This paper from The Lancet has the most accurate summary. I quote:
This means we've effectively passed two doubling times since there, bringing the total number of Wuhan cases to be ~300,000.In our baseline scenario, we estimated that R0 was 2·68 (95% CrI 2·47–2·86) with an epidemic doubling time of 6·4 days (95% CrI 5·8–7·1; figure 2). We estimated that 75 815 individuals (95% CrI 37 304–130 330) individuals had been infected in Greater Wuhan as of Jan 25, 2020. We also estimated that Chongqing, Beijing, Shanghai, Guangzhou, and Shenzhen, had imported 461 (227–805), 113 (57–193), 98 (49–168), 111 (56–191), and 80 (40–139) infections from Wuhan, respectively (figure 3).
2. Most 2019-nCoV cases are mild. While we still lack data and this could change, current estimates suggest 2019-nCoV seems to cause mild illness 80% of the time, complications 20% of the time, and death 2% of the time. It also seems to spare children, similar to SARS. This might seem like good news, but there's a downside to this. Coronavirus antibodies don't last very long, meaning you could be reinfected in a few years.
So what are the implications to this fact? Most cases are mild, so people with mild illness will go unidentified, spreading the virus to those around them. This means these big travel bans are unlikely to work (more on that later). 20% of cases become severe. If that happens to you while medical resources are strapped, you might not get the care you need, increasing the mortality rate. This brings me to number 3.
3. 2019-nCoV is almost guaranteed to become a pandemic. With possible cases in Wuhan alone, and give the fact many cases of illness are mild, there's basically no chance that this won't get out. Borders are too porous and the world is too interconnected. Focusing on mass quarantines and travel bans are wasting resources from the things we do need to focus on. So what do we need to do?
Dramatically increasing hospital's ability to treat a surge of severe patients is critical. We need hospitals to stockpile supplies like O2, gowns, masks, etc. We also need to rapidly pour research dollars into developing an on-site, rapid test. Quarantine at the city level won't work due to it being too porous. However, isolation at the individual level will slow spread. But rapid isolation requires a rapid test.
What about a vaccine you ask? That might take at least a year to develop. But we still might need one because...
4. 2019-nCoV may become endemic. Rapid infection across the globe, combined with the fact you can be reinfected, means this disease might not wipe itself out. It could easily go in waves, mutating/evolving as it infects numerous people. Usually this means the disease becomes less lethal, but not always (Spanish flu got worse). Coronaviruses are usually less prone to reproduction errors, due to some special proteins they have to check their RNA, but errors still happen. Looking at future "corona season" on top of flu season is not unlikely.
A vaccine will help though, and by the time it becomes endemic, we might have one developed. That will give you individual disease resistance at least.
5. What does this mean for you? While a 2% case fatality rate may seem low, 2019-nCoV infection obviously does more harm to the elderly and those with per-existing conditions. There's also a sizable number of young, healthy people who die too, and we don't quite know the clinical factors yet that lead to death. This is a novel disease after all, and this information could easily change. So we don't want to underestimate the damage this virus could do to human life.
While large quarantine efforts usually fail due to porous conditions and human error, you can still reduce the odds of contracting it through social distancing. Don't think you're safe just because the virus isn't in your city yet. We lack the capacity to rapidly test, and health authorities are only really testing for cases if you've had recent contact with someone from Wuhan. But if the virus leaks out of Wuhan to somewhere unknown (highly likely), and that person infects another person, who only shows mild illness, and then you have contact with that person, you could still easily contract it. You might not die, but even mild cases can be pretty miserable. There's something to be said for not lying sick in bed for two weeks and then giving it to your elderly grandmother.
So practice social distancing where you can. Avoid crowds, especially avoid contact with sick people. Wash your hands, and if you get sick, isolate yourself.
At least that's what the coronavirus task force said in their public briefing yesterday. Still I wouldn't hold my breath on the vaccine because spinning up massive manufacturing takes time, and they'll probably distribute it to health care workers first. (You may want to hold your breath so you don't inhale the virus 
)