I'm fairly responsive to comments left on my answers. This often means updating an answer to incorporate new information or questions that have been added in the comments (or edits to the original question).
It would be useful to flag comments as 'addressed by edit', so that they can be deleted by the commentator, or highlighted for pruning by mods - I don't think this is in scope for the usual 'flag comment'.
More contentiously, it might make sense if comments flagged with 'addressed by edit' were automatically suppressed after a suitable period of time has passed - long enough to rule out silliness with duplicate comments being used to steal comment upvotes.
EDIT I'm not convinced that "This would mean that in the long run, you could delete any comments on your posts without involving others" would be a problem. It is a valid point, so the safeguard would be to have a veto, so that when a poster says 'addressed by edit' the commentator can say 'no it isn't'.
I can see there is still an argument that comments add to a SO users (offline) rep, however I believe mods clean-up posts anyway to remove comment noise, so I don't think anything is really lost.
Moving on to the concerns complicating the UI, I happily concede that a flag next to comments would be the wrong place. Presenting a list of comments plus checkbox at edit time would work, and should improve quality (as comments become prompts when editing).