I could see some scenario where Hillary wins the first fifteen primaries, then has some stroke/health episode, and the convention is drawn into chaos because Hillary still thinks she’s healthy enough for the job.
Note....she hasn’t released any health records and I’d wager a fair sum of money that she won’t ever do it.
Here is Fauxahontas practicing her Democrat Convention grand entrance.
https://www.youtube.com/watch?v=6XiK6ioThDk