Should we transition to making our conference online or postpone?
Great question; however, I don't think there is any consensus opinion as to how good online conferences are. 

You might, however, read this blog post by Daniel Litt. He was an organizer of the Western Algebraic Geometry Online conference, held via Zoom this April. It was quite large, with around a thousand participants, and in my opinion very successful. 

In his blog post he discusses what went well, what went less well, and what the organizers tried to achieve. In summary, the organizers weren't able to replicate everything good about an in-person conference, but overall they succeeded in creating a very valuable experience for the participants.