It is true to in Wayland you can write protocol extensions or custom compositors to get around these limitations. However, what many fail to realize is that the primary challenge in Linux accessibility is not just a technical problem as it is getting people to actually implement specs and care about it. Even with atspi itself, a standard that has existed for over a decade, major apps like Firefox often do not implement the atspi Collection interface. This is not a criticism but rather a practical statement that accessibility needs to be standardized and easy to implement for it to actually have any use. Orca works on Wayland but only in certain compositors. For assistive technology software developers, this pattern of supporting specific compositors is not feasible. It is important to understand that we need to support assistive tech generally. Not just ad hoc extensions for certain types of disabilities.
Wayland has no concept of global coordinates or global key bindings. The protocol itself is designed around atomicity which is a nice concept, but is fundamentally in conflict to the need of assistive technologies to control the entire state of the desktop globally. As such, atspi methods like get_accessible_at_point are impossible in Wayland.
I agree that X11 cannot be carried on forever, but with the current state of Wayland, the phasing out of X11 will have the effect of drastically harming the accessibility ecosystem. Accessibility is not a "nice to have", it is essential to the mission of community inclusion and wider goals of adopting desktop Linux in education and government.