Elizabeth Warren is not a socialist, and that matters, for reasons I have outlined previously. That said, to the average voter, she sounds a lot like Bernie Sanders; the right will exploit that ruthlessly if she is the nominee. How should she make the case that she is just a capitalist reformer?
By combining Piketty with American history. She can argue that American capitalism has always turned into oligarchy in the absence of extensive government regulation. The first wave of oligarchy, the Gilded Age, ended with the Progressive Era; the second with the Great Depression and the New Deal; and the third one started with Reagan and continues today. Capitalism survived the first two waves in good order, and it will survive her, too.
To me, it is a pretty persuasive case, and it puts her in a context that is less alien and threatening than Bernie’s socialism.