The latest beta for the upcoming WordPress 5.0 release is now available for testing. Note that this is a DEVELOPMENT release and not something to install on a production site unless you want to invoke the power of chaos.
The actual production release of WordPress 5.0 is expected around November 19th, pending of course any major issues.
Here are some of the changes in beta 3:
For more info on the upcoming WordPress 5.0 release which brings the dreaded Gutenberg editor into the mix, check out https://wordpress.org/news/