Considering the usefulness of this extension, I've decided to open source Realtime. The thought has been playing around in my head for a while, the pusher extension clearly has its drawbacks and there's so much more possible with websockets that we haven't even drawn upon.
After a short discussion we have accepted this extension into a warm embrace as a first-party extension under the Flarum core team itself. Though there are still some changes to be made, the PR itself has already been opened ( flarum/framework4295 ). As a result you will soon see Realtime as part of first party extensions line up for 2.x.
Realtime, as many other extensions I've authored originally (Upload, Byobu to name a few), holds a very special place in my heart. Built to fulfill the needs of the many, sprung to life with as little fanfare as possible, but already used by many.
I hope that Realtime will be much appreciated and nurtured to remain a powerful feature of your community.
Please note that for 1.x Realtime remains a premium extension and as such available on the Flarum Extension Market.
Also a big thank you to @IanM for assisting with the refactoring of Realtime for 2.x.