Sadly none of the testimonies will make any difference. Trump supporters live in a parallel universe in which facts and reason play no part. The Senate will not impeach Trump, his supporters will complacently continue to cheer and howl at his rallies, he will win re-election in 2020 and the USA will continue its descent into abject dysfunction. Far more importantly, a much more self-controlled and clever person is waiting to take full advantage of the truth Trump has accidentally taught the world: that provided you stick to simplistic atavistic messages that rouse fear and hatred, and provided you keep your messages short and easy-to-understand (simple minds crave simple ideas), you can gain half the population as supporters (the low-IQ half) and thereafter they’ll stick with you whatever you do because changing their minds based on evidence is beyond their cognitive abilities. That’s how almost all tyrannies happen and the USA is no exception.