While I feel that moderator should use their privileges as sparingly as possible, I don't feel comfortable with the way things are currently heading to. Instead of completely stepping back from abandoned questions, I feel that moderators can play a supportive role, like giving feedback to the people flagging questions. No one likes to be ignored.
Saying that, if you think you have flagged or cast your close votes on abandoned questions and they are not sufficiently acted upon, you can do other things that will determine the fate of the question.
Like downvoting. If the question falls under certain conditions, then it becomes a candidate for automatic deletion. You don't need to worry too much about garnering 5 close votes for it when a single downvote is all it takes to wipe it off the site. (I already did propose downvoting for a similar situation, but people didn't prefer it.)