Inside Higher Ed on the future of academic conferences: https://www.insidehighered.com/news/2021/09/13/future-academic-conference
A significant fraction of academics surveyed said that they still felt unsafe going to physical conferences, and with the carbon footprint and reduced expenses of virtual but greater interactivity of physical meetings, some mix of both seems likely going forward. However, trying to mix both in one conference (especially for conferences with many parallel small talks or panels) seems difficult and expensive.