No one here knows. And those who know don't tell etc.
Photoshop is 10-bit ready, so it's probably just a matter of time. But it's Windows only, you need a 10-bit capable video card and driver, and only a very few expensive monitors are true 10-bit. I'm sure you already know that. But the point is that it would benefit a very small part of the user base, so that probably pushed it downwards on the to-do list.