While discussing the views UI with mgifford we realized that states itself is not really accessible, as these elements
aren't important in the firstplace but later (based on some actions) they appear and so can be accessible. (See #843708: Add option to set caption & remove summary in the html table (Accessibility) as example)
Drupal has a nice tool to announce changes: #1959306: Drupal.announce does not handle multiple messages at the same time; Improve the utility so that simultaneously calls are read. but it's not used in states.js