Apple is testing a bunch of new features for iMessage that could be released with iOS 14. This includes a new mention system where users will be able to catch the attention of a particular person by using @ and then typing their name. This will then send that user a notification even if they have that group muted.
Whenever a user would use the @symbol, iMessage will show all the contacts in the conversation in a UI similar to how Slack does it currently. Additionally, Apple is testing allowing users to retract/delete sent iMessages. However, a message will be displayed to both the sender and the recipient that a text was deleted. This implementation is similar to how the feature currently works in WhatsApp.
Apple is also working on other new features for iMessages like typing indicator for group chats, the ability to mark the last message of a conversation as unread, and an expanded “/me” command for sharing status updates. These features should also be available in the Messages app in macOS 10.16. The improvements could end up making iMessage a viable Slack and Teams replacement for many. However, it is not yet confirmed that Apple will ship iOS 14 with these improvements to iMessage. The company could very well delay the release of these features if they are not ready in time for iOS 14 release.