My bet is that it will be Trump versus Biden in the presidential election of next year. It is a fairly obvious forecast. It is unlikely -- although it is possible -- that Sanders or Warren could take the Democratic nomination, but we shall see.
Biden is going to get a major headache from the "progressive-left" which has huge influence within the Party. This is mainly due to the fact that the American Left is, outside of political Islam, the most racist political movement in the United States. It is also THE most racist political movement in the US with significant political power.
Thus Biden will be derided by the Democratic Party base as too old and too "white"... whatever that means, specifically. And they will do so without recognizing their own bigotry toward the guy.
Therefore, Biden will need to hold off not only the Republican Party but the Democratic base, as well.
I neither voted for Trump, nor did I advocate for him, but my prediction is that he will win in 2020 for pretty much the same reason that he won in 2016. And this time I might vote for him as a protest vote against The Haters, i.e., those who despise "whiteness" and "toxic masculinity" and "Zionists."
If the Democratic Party loses in 2020 -- which is my prediction -- the most significant factor will be "politically-correct overreach"... particularly on the campuses, both high-tech corporate and academic.