I know sometimes when there's some to and fro, you get a link offering a chat. And comments are imported into it.
But other times a chat is appropriate and because of no to and fro, it doesn't come up.
In the case of the comments on this answer , some comments may well be very useful, but already after the second comment a mod wrote (understandably given the rules!) "If you want to discuss something, create a chatroom please. Otherwise I'll have to purge the comments here. Comments should be used only to ask for clarification or point out mistakes in a post."
In such an event, it'd be good if comments could be saved and a chat be had. I made a comment offering a chat link (as the mod intelligently suggested), but the chat doesn't import the comments.
Perhaps a good feature would be the ability for a commenter to spawn a link to a chat room that imports the comments. Or rather than purging or threatening to purge comments, if mods could create a chat link that imports the comments.