BTW, I wish there is a way to upgrade a comment into a post and automatically move all the discussions under the new post as well.

The only reason I can think of to upgrade a comment to a post is to draw attention to it, whether google attention, naturality of external linking, or the attention of the regular readers. In all these cases, it seems to me that it is the duty of the author, who is demanding time from many readers, to spend time summarizing the old discussion and making it easy for new readers to join.