What happens if a pandemic hits?

What happens if a COVID-19 coronavirus pandemic hits? What will the repercussions be if the virus spreads worldwide? How will it change how we live, work, socialize and travel?
Don’t get all disaster-movie here. Some people seem to have the notion that a pandemic will mean shutting down borders, building walls, canceling all air travel and quarantining entire nations indefinitely. That is entirely incorrect. Containment attempts can slow down an outbreak and buy time to prepare, but if a p