Oprah for president? I guess, but I doubt she actually could win. Her reason is Trump did it, so...
However the problem is that she thinks Trump won based on celebrity, but that's not the case..He won on message, which resonated with voters. Issues that Americans found important which they have been against for some time now.
The voters who voted for Trump did so because they're tired of the way the country was heading after four years of a far left wing President, who at the the time of his departure had a 29% disapproval rating on most polls when it came to "direction of country". No matter what Obama's popularity was, it was based more on celebrity than anything else (and some polling juice), and when Trump came along he pushed back at Obama's agenda, thus Trump won the election. Oprah's agenda would nothing more than a flashback to those unpopular left wing agendas that Obama shoved down the throats of American and would likely be rejected outright.
Right now the Democratic Party is in a shambles. After the election they added to that destruction by descending into chaos, and children's games which have only infuriated most Americans, instead of just moving on with the loss. Polls have shown that Americans have grown weary from the "lost the game so I'm taking the ball and going home" approach they've had to the election and a recent poll showed they just want them to stop it and begin cooperating Republicans to get things done. They won't, this is guaranteed by their leadership constantly playing games and acting foolish, and the Democrat Party will continue to head down the crapper.