Most organizations don’t have the resources to let people travel without an actual event on the other end.

I could be wrong, but I suspect visas may be affected as well.

The organizers and attendees will try and coordinate something else. However, throwing something together on zoom, at such short notice is going to be a crap show.

The schedules wouldn’t survive unscathed, since speakers will start dropping out at this point.

If they do manage to get something together, they run the real risk of it being a rickety and frustrating event.