“ It’s been functionally replaced by messaging, chat, and DMs, effaced by social media”
No it hasn't. In business communications, social media is limited. Tens of MILLIONS do not use it, and many of them are in some form of business. There are also legal requirements re contracts, signatures etc., that are not met by social media.
You seems to be living in an imaginary world. Open a window and look out, the real world — and eMail — is out there. Look around you in that real world. Look at those who are welded to their phones - they are NOT everyone, not even close. Millenials and kids, not the backbone of real industry.
The only social media interactions that I have are from friends and family, never business - and I’m heavily involved in publishing in lifestyle and technology areas.