It's already clear to me from watching Jonathan Turley defend the president against obstruction of justice charges that the criminal defense for Donald Trump is going to rely on the fact that a person who doesn't know right from wrong doesn't necessarily have criminal intent if they do wrong. Turley, for example, blandly explained that the way that Trump acted towards Mueller isn't much different from how he acts against any number of officials who he fires or threatens to Fire. He's always pissed off. He wants to fire John Kelly and Don McGahn and Jeff Sessions, but he doesn't. He's always doing improper things that violate norms, so it's not necessarily true that his intent is to intimidate career FBI officers into not testifying against him when he names them publicly and sends his goons after them.
If there is an impeachment trial, I expect that Turley will defend the president. He'll be a lot more effective than Dershowitz would be, I think.