Based on the stability, testing, and reports on the release candidates for WordPress 5.0 so far, we are now targeting
As before, if new information arises that indicates the software is not stable, we will adjust or remove the target date.
What if I don’t want to update on that date, or I’m not ready?
That’s totally okay, there’s nothing that says you must update the moment there’s a new version released. You can push the button whenever you’re ready.
What if I want to upgrade but I’m not ready for Gutenberg?
No problem, install the Classic Editor plugin and 5.0 will be indistinguishable from 4.9.8 for your posting and editing experience, and you’ll still get the other improvements and fixes that have gone into 5.0. Classic Editor is supported until 2022, and now allows you to switch between Classic and Gutenberg on a per-user or per-post level.
Over 1.3 million .org sites have already opted either the Gutenberg or Classic Editor plugin, which is more than run any single version of WP prior to 4.7! Those sites will notice nothing change besides a version number.