Mentions
Many of the features seem to be focused on improving group chats, which is certainly an area where iMessage remains a bit weak compared to competing apps like Facebook Messenger and Slack, but Apple plans to close this gap by offering up a mention system that would let users tag group chat participants by using their name, in the same way this feature already works in other group chat apps.
Typing an “@“ sign would bring up a list of suggested contacts, and users who are tagged in a group chat would presumably receive a higher-priority notification. This would be hugely useful in busy group chats, where conversations get muted because of all of the noise. Apple would presumably add an extra setting, either globally or on a per-chat basis to allow users to choose to receive only notifications when they’re mentioned.