I agree with the above.
Having said that, I think if you were a foreigner in a country that goes into lockdown, as long as you had the cash, you could still fly back to your home country.
I say 'have the cash' because prices of flights go up by 2 - 2.5x.
Obviously this is dependant on the country. I heard of an (Aussie) Australian who was stuck in India and go caught up in their bureaucracy overload. State, local and federal government all contradicting each other on the ever changing rules. Still eventually got out but it was a hell of a time. But, if you were in say a European country, I think it would be 'OK'.
My bet is they'll ground flights soon from most places, like spring.