Sway would have great potential as a digital signage system
I think Sway could have the building blocks for a great digital signage system. If Microsoft could release a "Enterprise" product where digital signage content could be created, and then be able to distribute them to TV's using a Windows 10 IoT device, that would be amazing. Storage of content could be either OneDrive, OneDrive for Business, SharePoint or on premise server. Would need to separate the management of the connected Windows 10 IoT devices (IT department) from the content creators (your Communication department), then you got a great corporate digital sinage system.
We're currently using this for signage, but it has a long way to go. It's a more display-friendly version of a PowerPoint slide show, but the ability to integrate dynamic content (i.e. Yammer, SharePoint, etc.) would be even better, and allow for more responsive updates to employees.
Dan the LAN Man commented
Each digital sign would probably need a licensed "player." Is there such a thing as a Sway player and can it be freely distributed?