According to Alessandro Paluzzi, who frequently reverse engineers meta social media apps to discover new features, Instagram could introduce a way to share comments on other Instagram posts in threads.
Paluzzi shared an image showing that when commenting on an Instagram post, there might be a new dropdown menu that will allow users to choose whether they want to share the comment only on Instagram or “also share in threads.”
Meta has taken some steps in the past to integrate Threads into its other platforms, such as showing Threads posts on Instagram or Facebook (and later giving users the option to opt out of them). While the Twitter-like short-posting social network doesn't have its own DMs either, users can still receive or send messages through Instagram.
The bigger effort, of course, is Meta's slow work to integrate threads into the Fediverse. The company's measures include the ability to actually see Responses from the Fediverse under their posts and, more recently, under the posts of others.