I think people would at least appreciate a heads up from ED so we aren't all running around wondering if this is a bug and caught off guard. I don't expect a heads up for EVERYTHING but this seems to be pretty big change.
Maybe in a newsletter, just say, "We will be making changes in the future to how keybinding is done in DCS in an effort to make it more streamlined, this may impact current keybindings." Then maybe offer a workaround if you want to keep your old keybinds.