In approx. 40 days (or less), WordPress will roll out the 5.0 version update that comes with Gutenberg. The Gutenberg is a built-in visual editor and page builder that allows you to easily make all the content changes without using any third-party plugins (or page builders, such as Elementor and similar).
The purpose of Gutenberg is to create a more user friendly editing environment, but from what I can see, it will cause more headaches than any other WordPress feature.
The problem lies in the fact that majority of WP sites/themes are not compatible with Gutenberg. An update to 5.0 version may completely break your site! If you end up having issues with your content, you’ll have to either redo an entire theme or to fully disable Gutenberg.
The easiest way to disable Gutenberg is by using this plugin: Disable Gutenberg. I recommend you to install it and activate it right now, before Gutenberg replace your classic editor.
It’s also highly recommended to do a full backup of your site while you’re still on 4.9.8 (or 4.9.9) version of WP.