User blog comment:DaNASCAT/Technical Update: October 21, 2015/@comment-3388044-20151021220414/@comment-126761-20151023094902

As I understand it, it would simply revert you back to the plain wikitext editor. The change also expands the preference to cover CSS/JS pages as well.

Regarding the complexity of having different editor types: agreed, fewer is better in the long-run. These tweaks should make the behaviour more predictable, at least.

Eventually it is likely we will have: classic, classic + syntax highlighting/code editor, VisualEditor. The first two are relatively simple to support - at least when compared to VE (or the classic visual mode).