If nothing else, this tells me that the Clinton campaign originally thought they'd effectively be declared the winners early in the evening, but aren't so confident about that anymore. I suspect Pennsylvania and Michigan are now making them very, very nervous.
I would not be surprised if the networks called the election for Hillary with a very small percentage of the vote in. I still expect when all the votes are in we have a Trump win. I will hang in to the end.
I think it is even worse than that. Maybe a 9:30 display would be considered too early. But.....if they knew that they were going to win, then they could just delay the display until 11:00 pm or so. No big deal if they have to delay it.
HOWEVER, for them to cancel the fireworks display in its entirety over 1 day out really says something about the campaigns internal polls. I think it is clear to them that it is a lost cause.
Look at the body language of the candidates and staff today. Right about now, will be able to see one with confidence and one with dejection.