>> Are there any plans to update redactor to redactor X or CKEditor to version 5?
CK Editor 5 is not free, so I deliberately stopped at 4.
Redactor is shipped under an OEM license which I got from them (which allows you to use it for free).
It's also very not cheap. I'm not sure there's a need to update that at this time.
TinyMCE got impressively complicated to use, and understand, so I also stopped updating that.
Generally speaking the editors have a habit of breaking existing code when you update them. As i don't want to gratuitously break existing apps, I'm fairly cautious about upgrading the editors.
Of course nothing stops you implementing the editor of your choice. They're all just JavaScript plugins, so it's reasonably straight-forward to do - especially if you only have your own site to worry about.
Cheers
Bruce