Why he probably won't: Like almost every candidate on Nader's list, Steyer has never sought elected office previously. Bankrolling the campaigns of candidates who will help spur movement on your issues is one thing. Engaging in a years-long cross-country presidential campaign is another thing entirely. So far, Steyer hasn't come close to signaling he'd be up for that.
Why he could: A true media mogul, the CNN founder has publicly flirted with the idea of seeking the presidency in the past - telling reporters in 1998 that he was "very seriously" considering mounting a presidential bid. At the time, he said his presidential ambitions were fueled by a desire to change the world, and he was apparently prepared to set aside $75 million of his own money for the campaign.
Why he probably won't: Turner has spent decades in the public spotlight and over the years has made several controversial comments that would be perfect fodder for political opponents. Once he called those who observe Ash Wednesday "Jesus freaks." Perhaps a more compelling reason Turner would sit out 2016: he'd be 77 years old by Inauguration day.
Why she could: She's Oprah! America's most beloved talk show host has the kind of name recognition that most presidential candidates would kill for. She's known nationally and internationally, as well as among the Democratic donor base - especially in her hometown of Chicago.
Why she probably won't: How many politicians are, truly, "beloved." If you said "zero," you're right. While an at-times probing interviewer and outspoken social advocate, Oprah's brand has benefited largely from her non-polarizing demeanor. By entering the political arena, Oprah would open herself up to a new level of scrutiny, criticism, and attacks that it's hard to imagine she'd be eager to take on.