There's some fairly damning stuff in the latest leaked DNC emails. Washington Post, CNN, NY Times, etc. are all picking up on the story.
1) Journalists sent articles to DNC for their pre-approval
2) Sanders' campaign described as the "insurgency"
3) Debate about whether a Sanders staffer should be denied entrance to a Debbie Wasserman Schultz event
4) Discussion of whether to smear the Sanders campaign by painting it as "a mess"
5) Discussion of whether to smear Sanders in religious states by painting him as an atheist (in a practical sense he is, but that's not the point)
6) Top DNC official refers to Sanders' campaign as the "Bernie BS"
There's a ton more, but all in all it paints a picture of the DNC having decided their candidate from the beginning. I doubt it will affect anything except with the left (read: most young people), who already dislike and distrust her and are pissed about her pick of Kaine as a VP.