I think removing the annotations system is actually a good thing since they don't work on mobile anyway and 70% of my audience (and probably the audience that the majority of people have) == mobile users.
That said I do hope they add some of the features annotations had into cards. Things like showing text on screen, or highlighting a certain area of the screen, etc would all be useful for those times where you remember something you forgot to mention only //after// your video is already uploaded and released.