Right now, in Firefox/Mac, at all wikis where VisualEditor is enabled for my account, from read mode, I can press control-option-v to open a page in VisualEditor or control-option-e to open it in the wikitext editor.
I like this. I like being able to explicitly choose my editor, and I like being able to do it from the keyboard. I want these keyboard shortcuts to keep working exactly like they do now, regardless of which editing environment I used last, even when there is only one edit tab.