No matter what some people say.
Biden makes a certain amount of sense. After all, he's already won two presidential elections in the veep slot and is the sitting vice-president. He's certainly a better prospect for Democratic victory next year than Hillary Clinton.
But Warren makes no sense whatsoever, either on her own hook or with Biden.
Biden-Warren 2016 would be an east coast liberal ticket, which means they'd carry some east coast liberal states, California, and maybe -- maybe -- Minnesota and/or Wisconsin. If the Republicans could get their collective head out of their collective ass and dig up a plausible candidate of their own (yeah, yeah, I know, not very likely, but it might happen), they'd sweep the south and midwest and be competitive in Ohio, Pennsylania and Florida. The Democrats need a southern or midwestern figure on the ticket (my recommendation, if they're interested in winning: Russell Feingold).
Aside from that partnership downside, Warren is just a train wreck waiting to happen. She's been caught lying to manipulate academia's ethnic favoritisms. She talks like a populist, but she's personally a 1%er and politically a corporate welfare deal-cutter as bad as any she criticizes. And she's annoying in that very special way -- I doubt I'm the only person who can't see her without flashing back to Dana Carvey as The Church Lady on Saturday Night Live.
Warren would cost any Democratic ticket five to ten percent in the swing states. And that would be the election.