That's assuming XI2 will be able to send actual mouse (other devices) movements to requesting applications. Right now nothing can (DGA doesn't count it's not available anymore).
Can you get in contact with the Xorg mailing list on that issue? As far as I understand the XI2 plans raw input processing is planned and a high priority(not only for wine, but also to layer DGA emulation on top of it). I barely know the details, and since you worked on this it would be very helpful if you talked to the Xorg guys