If Hillary drops out, I don’t think most of Bernie’s voters will be happy unless it is Bernie.
Bernie took his money and quit the Democrat party. He's an Independent again. That isn't to say he couldn't suddenly have a change in heart and rejoin, but it's definitely a problem.
I sort of expected something like this to happen, but except for a debate this is just about as high-profile an event as she could have chosen. I'm guessing that brazen denial is about the Dems' best option. "Just a little fainting spell due to Trump, she'll be fine." The media will try, but I don't think it's going to work.