Donald Trump's primary mode of remaining relevant and making headlines is through vicious, childlike attacks. Judging from his past behavior, he will continue to use the "Crooked Hillary" moniker and ensure that he keeps the topic relevant in the media in an attempt to discredit her. Consider the fact also that this was not the outcome that the Republicans wanted, so they will continue to go on about this well until the election.
Following the incident with the email probe, Clinton's integrity is more questionable than ever. Trump has already accused her of bribery, and even without his intervention the electorate may have lost some faith in the Democratic candidate. Unfortunately, it is unlikely that Trump will let this opportunity pass because it might provide him with some much needed upper hand.
Donald Trump has every right to continue to publicize the misconduct of Hilary Clinton. She does the same to him regarding bankruptcy and blows it up out of proportion. Since he has over 500 businesses and only 4 have filed for reorganization under bankruptcy laws, Clinton delights in stating he's a total business failure. While he has not put the American nation under scrutiny by poor behavior, Clinton has done so repeatedly.
This is one of the few things that Donald Trump has had to go against Hillary Clinton, and just because no charges are being filed doesn't mean he's going to stop talking about it. He has a terrible campaign, and is running on nothing but ridiculous words and ideas, and he knows that his only shot is to make HIllary look so bad that people don't want to vote for her.