We suspended travel to China earlier than most. If something like this spreads easily, I really doubt they could stop it completely when you consider just how much direct travel there is/was on a daily basis. Unfortunately, it may be one of those things we won't know for sure until it has already happened.
The testing is what this administration and the CDC dropped the ball on. They just barely started screening flights from Italy YESTERDAY. Insane stupidity. Testing should have been ramped up weeks ago, with screening of flights from any hotzone that wasn't outright banned, including testing.
The genie is out of the bottle on this, but unchecked it could run wild through many of our cities. For most of us, it will be just the flu, or nothing at all.
But for those who get sick, many more will need hospital services that will overwhelmed. And the risk for death with comorbidity factors goes up a lot.