I asked Michael Williamson, the developer of the excellent Mammoth .docx Converter (without that plugin, my WP life would be different!) about CP future compatibility. Here is his answer:
“I don’t have much spare time, so it depends on how much effort compatibility would be. If ClassicPress continues using TinyMCE and the API doesn’t change, then I’d imagine it would continue working without an issue, since the integration with WordPress is reasonably simple.”
I assume that we can confirm that this will be the case?
Yes, I agree with this. We will not be changing the TinyMCE / editor APIs so I don’t expect anything to change here either