You can replace certain use cases of email, but you wont replace all the use cases at once.
For business opportunities might be around workflow and
decisionmaking.
Slack dramatically reduced my email volume by replacing a use case that email handled badly, for example.
A consumer analogy, Facebook replaced a bunch of email use cases. I still have a friend who sends out email updates with photos while traveling, for example.
SMS and messaging apps, of course.
Someone could do a map like this list of companies that replaced specific use cases of Craigslist
Facebook messages are lock-in. Back when I used it a lot, you could connect via XMPP client. But there is now no way to get your own messages out of their eco-system that I am aware off. It's like switching a dumb-cellphone to another cellphone, you loose all your old SMS (if the aren't stored on the SIM card and there is no PC link cable+software). Open standards like IRC, email, XMPP prevent something like this to happen.
For personal uses, email has already been disrupted by Facebook, WhatsApp, and instant messengers overall. Longform newsletters are the last real use case, because RSS failed to disrupt it. Facebook and others are working on that as well.
Comments
You can replace certain use cases of email, but you wont replace all the use cases at once.
For business opportunities might be around workflow and decisionmaking.
Slack dramatically reduced my email volume by replacing a use case that email handled badly, for example.
A consumer analogy, Facebook replaced a bunch of email use cases. I still have a friend who sends out email updates with photos while traveling, for example.
SMS and messaging apps, of course.
Someone could do a map like this list of companies that replaced specific use cases of Craigslist
https://www.cbinsights.com/blog/craigslist-unbundling/
Facebook messages are lock-in. Back when I used it a lot, you could connect via XMPP client. But there is now no way to get your own messages out of their eco-system that I am aware off. It's like switching a dumb-cellphone to another cellphone, you loose all your old SMS (if the aren't stored on the SIM card and there is no PC link cable+software). Open standards like IRC, email, XMPP prevent something like this to happen.
For personal uses, email has already been disrupted by Facebook, WhatsApp, and instant messengers overall. Longform newsletters are the last real use case, because RSS failed to disrupt it. Facebook and others are working on that as well.
The op's question was about business though.