Nikon has set the bar pretty high with the Z9, so Canon will likely be looking to better that unit. Biggest question for me is the shutter and sensor. Global shutter? If so, what limitations, if any? And how to improve an already excellent AF system? There's room for improvement, but what? Subject detection and tracking? While this isn't a camera I'll ever buy, I do like seeing the state of the art pushed.
IMO, the big rumor-news items are the global shutter and the quad AF. I also don't see the 'hearts and mind' competition as solely the Z9 but the flagship Sony as well. My instinct (I have no stats) is that if Canon leaked customers to other marques, it did so to Sony rather than Nikon. Other rumors such as the screen being .8" larger than standard or its menus being in color strike me as interesting but not solid points that will aid the snapper to perform better.
I suspect we'll see a street price of U$7,500 or so as well.