Enterprise chat, sometimes referred to as team messaging, has emerged as a viable alternative to email and might just knock it off its throne. At the very least, there is the potential for enterprise chat to absorb much of the communication that is now done through email.
Since the emergence of email as the primary form of corporate communication, everyone has complained that there is too much of it. What knowledge workers really mean (unless they’re talking about spam) is that it is too hard to use for the way most people want to communicate: What they seek are conversations, not electronic letters. 
Before email, corporate knowledge workers wrote memos (on paper!) for insiders and letters for outsiders. These forms of communication served the corporate hierarchy of the time. Memos went up and down the chain of command, and letters were formal messages between the company and its vendors and customers. 
Email was originally a reflection of that culture. As corporate culture became less hierarchical, email came to be used more and more for less official communication, effectively replacing conversations that would in the past have required a meeting – or at least a water cooler. But email is an unsatisfying medium for informal, conversational communications, because it was designed for more formal, letter-like statements.

Tweaking the Model

There have been a number of attempts to change the way email operates, usually by changing the email client. Google tried valiantly by linking emails into conversations, a method since adopted by just about all email clients. Alas, it still didn’t change the basic way that email handles communications – with signatures and headers and all of the proper parts of a letter. 
More recently, IBM has come up with a way of taking an email chain, stripping it of the parts that don’t matter in a conversation, and presenting it more conversationally. That may be fine if you are an IBM Verse user, not so much if you use any other email client.