That’s a pretty interesting line of thinking, I actually like this idea. When the replies are shown directly beneath the post, hide them in the rest of the post stream.
Possible caveat:
It will only show replies, not replies to replies.
If post B is a reply to post A, and post C is a reply to post B,
and post B is hidden from the post stream and shown as a reply to post A
How do we show post C ?