Email
Email will (finally) be disrupted in the enterprise.
Enterprise messaging services have already begun displacing the need for email communication within the enterprise, and this trend is only going to continue. Real-time communication tools are naturally more collaborative than email, as they allow for back-and-forth communications that previously were only possible via voice communication. With efficient content sharing features being added to these real-time collaboration tools, they will effectively overtake email for convenience for internal communication.
The disruption that will occur in the enterprise will essentially cause a restructuring of how work is done. Employees will be able to collaborate in ways that maximize their time, cut down on back-and-forth emails and allow for more time to be spent where it is most needed, on the work, not the communication.