People will find it easier and easier to deny it. We are surrounded by fake information, doctored photos and you know that everything you see on the internet has to be taken with a massive pinch of salt. That will be the argument about all the information relative to the holocaust.
You can find any theory and its opposite with "reliable" sources online.
showing how many believe the moon landing happened most people who have an opinion haven't got the technical knowledge to make an inform opinion one way or another, they just chose a theory they read online and are running with it.
Then there's the political aspect of it.