Will the Coronavirus outbreak make schools close down in America?

Probably.
Either because rumour will cause panic in some and so a closure will be seen as a'precautionary measure' by Principals.
Or through fear of being sued for not taking exactly that action if a case is found 'nearby'.

Not unless health authorities massively over react. It’s still manageable. Don’t be panicked by the 24hr news coverage. Look at the facts very clearly. Compare different news sources.

we haven't scratched the surface of how bad it's going to get