Absent a smoking gun email they will have a really hard time proving a crime on the classified information part. That article assumes storing classified info in that fashion is inherently a crime, but I don't think it is in this situation.
BUT emanations and whispers are suggesting the Clinton Foundation issue might have more legs. I know the FBI has a massive team devoted to both matters though, suggesting this is a real effort and that, if they come across actionable info they will take action. That's a very good thing IMO.