Discord Launches Threads
The ideal thread implementation is in Flowdock (which not many people have heard of or use), but it's really the best of both worlds.  Everything is a single stream of messages, and you can optionally group things as threads.  There is a really nice blending of the two.  Here's their implementation and you can see how well this works in practice.  http://blog.flowdock.com/2017/08/31/the-1-customer-request-h...Far far better than other abominations like slack - which hides streams of conversation behind a wall, making the UX terrible.