It's (now apparently) not a question of whether Bernie Sanders will run, it's a question of whether or not he will run under the control of the Democratic Party....
Sanders has a bad (from a progressive perspective) record on Israel Palestine.
For give my cynical lens. I am thankful that Sanders is speaking out and raising the discussion about the issues that he is talking about. I question, though, his sincerity and his ability to effect the change that is necessary. The issues that he should raise in a primary will be forgotten after the coronation. During a major campaign the issue goes back to the 'lesser of two evils'.
As this article points out
Let us be realistic: If Bernie Sanders raises issues to Hillary Clinton and the American public for a few months during the Democratic primaries, it will not change the course of the Democratic Party one iota. This is true in the same way that the raising of issues by the likes of Jesse Jackson, Howard Dean, and Dennis Kucinich (twice) in the Democratic primaries did not change the course of the Democratic Party, nor have these candidates and groups such as Progressive Democrats of America been able to significantly influence President Obama's policiesnor has the Progressive Caucus, for that matter, the largest Democratic caucus on Capitol Hill. And liberal commentators think Sanders will?
Sanders is being used as bait to attract progressives to the Democratic Party nothing more and nothing less.
I value my membership in DU and hope I don't lose it for saying the above.