Folks here have raised the issue about air conditioning—and it is valid—so I will predict that southern cities will spend beaucoup bucks retrofitting buildings to allow outside ventilation to get into otherwise sealed modern buildings.
So the folks in the south will be sweating, but they will be safe.
One more crazy prediction:
The virus will rip through Southern Hemisphere areas approaching their winter (think Australia, for example) and parts of those countries will be locked down with strict quarantines.
P.S They will blame the US for failing to stop travel to their areas in time.