Not only will die hard supporters on either side be suprised about who wins the election, but smaller elections will also hold suprises. There are also some pretty big ballot measures that are up in different states which could have a suprising outcome. It remains to be seen what will happen.
Throughout history all other candidates who have lost the election have given a concession speech congratulating their opponent who they had just lost to. Even during very close or questionable elections such as when Al Gore lost to George Bush in 2000.
During the Third and Final debate of this election season Donald Trump said he would "Leave us in suspense."
He might not accept the loss. Especially since he's been feeding his voter base that the election is rigged without any hard evidence. The burden of proof falls heavily on him in this situation.
Yes, on election night some people will be surprised. It could be that the final tally will be closer than expected, or one of the candidates will end up winning by a landslide. It's also possible that some states expected to vote for one candidate will end up voting for another.
As a country, we have the two most unpopular candidates ever. There's really no choice, but we look like a bunch of idiots. Trump is a bigot, sexist, racist blowhard who has no experience and apparently no real desire to to any of the hard work of being President. Hillary is the only actual choice. I can't wait for this to be over.