Currently, if an answer is posted while you're writing one of your own, you get a big notification about it. I think it would be useful for the concept to extend to comments and edits. Maybe the question originally had two interpretations/solutions and your answer covered both, but a comment or edit has ruled out one of them. Maybe an assumption you were making has been squashed, or something someone said has provoked an additional insight.
Of course, in most cases comments probably aren't worth the Bar Of Page-SlidingTM, and most edits are corrective rather than informative. Still, the use cases seem reasonable.