It is hard to predict the future, but here are a few ideas. Right now, it is a contest between Bernie and Biden, maybe with Bloomberg thrown in as a wild card. That said, I see three main possible outcomes- 1) Bernie wins a majority of delegates before the Convention, 2) Biden wins a majority of delegates before the Convention, or 3) Bernie and Joe both split the delegates fairly evenly, both have a plurality, neither has a majority.
[Correction- what I meant was that neither candidate would earn enough delegates to secure the nomination before the Convention.]
I think that the third option right now is the most likely. If Biden and Bernie both have a lot of delegates, but neither has a clear majority, the Convention will decide who the candidate will be. My prediction is if this happens, the first ballot at the Convention will confirm neither candidate.
Once delegates are released and Super Delegates are in play for the second ballot, Biden will win on the second ballot. He will then become the nominee. Then a lot of the Bernie supporters will be upset, yet still many of them will vote for Joe in the General Election. So, my prediction is that Joe will get the nomination, and then will go on to defeat Trump, whether narrowly or decisively, I do not yet know. We shall see.
[Edited]