Otherwise, email still used 'a bit' but only because no one else uses it socially anymore.
Calendar is never going to go away. You can call it calendar, diary, facebook events, reddit reminders but it is still the same thing - a way to work out what you need to do for the day, and remind you to do something in the future.
As a consultant I work with multiple clients at a time. Sometimes I have to accommodate their tools (such as Slack) and processes but email and calendar still are the lowest common denominator for communicating and staying in touch.
I actually prefer traditional email and calendar because those are open, federated protocols that allow me to use my own infrastructure and tools rather than relying on the client's infrastructure.
Juggling multiple Slack (or similar) accounts is cumbersome and doesn't integrate well with other tools and external processes (integrating one Slack account into your process usually works pretty well but as soon as there's more than one account things get messy).
In my personal life, maybe 10% email and very little calendar. The rest is filled with whatsapp, line, etc. I forced all of my friends to either whatsapp me, email me, or don't hear from me.
For personal life, not much email for correspondence (~10%?), but 100% calendar (private paid email and calendar).
I don't use any social network, rarely use my phone and emails are the easiest to note, sort etc.
Even with family, I exclusively use e-mail.