I have both Biden and Trump dead, but not assassinated, before 2021. Almost a week apart from each other. Trump goes into intensive care from exposure to Covid-19 around October 25th. Biden has a brain aneurism and dies November 1st. Trump succumbs after winning the election November 5th. Pence becomes the 46th President of the United States.
There is only 20.2% chance that happens by my variables. But this is 2020... so...