We posted about these upcoming changes on the forums and in our official API documentation about a month ago. We may consider creating something like a chat-dev mailing list to make it easier to discover these kinds of updates if developers would find it useful (give us feedback!).
You can find the complete list of our caps and other IRC behavior here: https://github.com/justintv/Twitch-API/blob/master/IRC.md
If people start requesting more granular caps which make sense for our system, we’re always open to making changes, so please keep the feedback coming!