My kid's school teacher has made WhatsApp official means of communication. They have created class-wise groups on which they send Zoom meeting details for online classes, as well as other school updates. This is followed by all classes and their respective teachers. So not sure when they would stop using WhatsApp.
Similar I am part of Society group, job update group along with personal groups like friends group from college, past companies, family, etc, etc. Would be hard to part away with all these.