I'm pretty sure Oprah has no intention of making a presidential run. She has a good racket going, won't want to alienate half the country, and a shot at the White House is usually a mean, exhausting, and expensive slog. If I had to guess, she'll settle into a low-level kingmaker role, and leave the heavy lifting to someone else. I said this back when she was floated as a potential Trump running mate in 2015, said it again last week, and still believe it.
Those closest to her may be sending mixed messages, but I suspect that has more to do with hangers-on wishing she would take them to Washington than it has to do with her intentions.