What we can do besides wringing hands is speak about Mueller's Witch Hunter history to one and all, day in and day out. Your friends, your Congressmen, the talk shows.
Also, I do believe there are measures to clip the wings of Deep State. Give Congress authority to bypass DOJ, when charges are due and not happening. Pleading the Fifth amendment when testifying about your conduct on the people's payroll incurs instant firing and loss of all benefits, including security clearances. Telling Congress “I don't know,” or other stonewalling rhetoric results in obstruction charges. Failure to reasonably produce documents, or unauthorized redactions, results in automatic charges of obstruction and loss of pay.