There has been a reduction in "traffic," but not nearly as much as I anticipated. This chart is maybe a few days behind a fast-moving situation, but I find it somehow comforting that math "goes on." We haven't even yet descended to the annual Christmas lull.
Yes, I know, this is not a question, just a comment. To turn it into a question:
Q. Is MathOverflow more resilient than other StackExchange sites, or are they all only seeing a similarly slight reduction in activity?
Added 17Apr2020 at @GeraldEdgar's request, a different and perhaps more relevant chart:
An apparent increase in activity since mid-March.