Since the Bernie Sanders presidential campaign is almost over (I would expect Bernie to not have any mathematical possibility of winning a majority of pledged delegates after the June 7 contests), I, as a Bernie supporter, will give my honest thoughts about what will happen once Bernie exits the presidential race.
Bernie would likely drop out once it becomes mathematically impossible for him to win a majority of pledged delegates
While Bernie is talking tough about staying in the Democratic presidential race until the Democratic National Convention right now, I highly doubt that he would continue his campaign if and when it becomes mathematically impossible for Bernie to win a majority of pledged delegates. The only way that Bernie can flip superdelegates currently supporting Hillary to his column is to get a pledged delegate majority.
Bernie is not going to run as an independent or third-party candidate, and he would likely discourage any write-in campaign for him or anyone else
Any suggestion that Bernie is going to be another Ralph Nader is absolutely false. Bernie knows very well that America has a strong two-party system.
Bernie isn’t going to run for re-election to the U.S. Senate
Unless Bernie were to somehow win the White House, this will be his final campaign for public office of any kind. Although Bernie probably could run for additional terms to the U.S. Senate (in fact, Howard Dean, who is a Hillary-supporting superdelegate from Bernie’s home state of Vermont, has already endorsed Bernie for his would-be 2018 U.S. Senate re-election bid), he won’t do so for a big reason that I’ll explain later in the post.
Bernie isn’t going to endorse Hillary Clinton
Even though, barring some kind of miracle Bernie comeback, it looks as if Hillary will likely win the Democratic nomination by any reasonable standard, the Democratic establishment and the corporate media have been solidly against Bernie since he started his presidential bid, and he’s not going to turn around and endorse a presidential candidate who is an integral part of the Democratic establishment. Bernie almost never endorses candidates for public office.
If Bernie has any outstanding campaign debt, he’d endorse Donald Trump
Although I will vote for Hillary in the general election if she were to win our party’s nomination, and I'd never even consider supporting an ultra-egotistical bigot like Trump, it wouldn’t surprise me one bit if Bernie were to sell his endorsement to Trump. Neither Hillary nor the DNC have any interest in helping retire any campaign debt that Bernie may have (the Q2 2016 campaign finance reports will tell the tale about the state of the Bernie campaign’s finances), although Trump may be willing to retire Bernie’s campaign debt, if there is any. If Bernie doesn’t endorse Trump, the closest he’d come to endorsing Hillary would be to officially discourage any write-in campaign or vote for an independent or third-party presidential candidate.