Obama didn't release his birth certificate for one very good reason, he is very clever and Trump is very stupid.
The fact is that the Republicans will always invent some crazy idiotic 'scandal' that they obsess about and endlessly throw up smoke. The birther conspiracy was mind numbingly ridiculous. It would require someone to go back in time to plant the birth notice in the papers. Or for some group of conspirators to go to an enormous amount of trouble in order to make a particular black kid president.
So rather than release the birth certificate and let the Republicans invent a new scandal, Obama held onto it and let them obsess about a scandal nobody else thought made the slightest sense, knowing that he could knock their house of cards down any time he chose. Which of course he did a week before the Bin Laden raid which was guaranteed to end the story.
George W. Bush opened torture chambers across the world and collected photographs for a sick sexual thrill. Yet nobody ever talks about that. None of the people complaining about Hilary ever complained about GWB refusing to comply with Congressional investigation or the deletion of 5 million emails.
So here is what is going to happen. Trump is going to go down to the biggest defeat since Carter and he is going to drag the rest of his party down with him. And afterwards there is going to be a new civil rights act that prohibits Republican voter suppression tactics and the gerrymandering that give them a 5% advantage in elections. And by the time it is all done the Republican party will have two choices, either boot the racist conspiracy theorists and Trumpists out or face two decades in the wilderness.