Many people are really starting to believe that Trump could win the 2020 election and serve another four years.
Now that several democratic candidates are out, the field is reduced to Bernie and Biden. Warren is really not a contender. Rather than dilute the party votes, Biden and Bernie need to put their differences aside and focus on a ticket that will defeat Trump. Could it be Biden and Bloomberg or Biden and Amy as a ticket, perhaps. One thing is for sure, the sooner they consolidate their efforts and unify the sooner voters will have a clear decision to make.
There is even rumor that Pence my not serve as VP for the second term, so that could make things interesting from the other front.