If he does the deep state will have four more years to go after him. The DOJ/FBI and the CIA/NSA will be fully mobilized and completely unaccountable by the courts.
Trump will spend the next 4 years in court defending himself, his family and his business.
Trump knows this but he probably thinks that if he does not run they will do it to him anyway.
They have two years before the next election bumps the Democrat Progressives out. Their corruption is visible and ugly. Trump need to play a PR game now—Its a game he knows how to play—keep his head down and wait for the Democrats to poop on the people. He needs to pull back and re-arm. He will, I believe that they will try to use him as a scapegoat but time is on his side, not theirs.