If it ends up being like the flu season it should start to drop off by the end of March or early April.
If it is more like SARS, that started in China in November 2002, confirmed in the U.S. in March 2003 with increased numbers confirmed, it was the first week of May before it appeared no new cases were identified, and by late May travel alerts started to be lifted.
If it is more like H1N1 (aka, swine flu), it started in Mexico and hit in California in April 2009, WHO announced it as an imminent pandemic and FDA approves new CDC test by end of April, schools start closing in May, officially a pandemic in June, clinical trials start in July, October reaches highest level with second wave and vaccination campaign begins, December data shows vaccine works and is offered to anyone who wants it, January 2010 numbers drop but still positive findings for months, and not until August 2010 does the WHO declare the pandemic over.
You have to balance all of this against the fact 12,000 people die in the U.S. every year from the flu according to the CDC, and we have already lost 10,000 this year from the flu. In 2017-2018, it is estimated 61,000 died from the flu and 45 million were infected.
The overreaction is staggering and mostly media-driven. That said, since there is no vaccine available you have to take it very seriously, especially if you are older or have a chronic disease already. Another case where social media and the 24/7 news cycle is not helping matters, and the bald-faced politics on display by some is just pathetic.