Probably never. Despite what one may think of the Nazis, and despite the efforts of historical revisionists, the official account of their "evil" is all that Germans hear from the day they first sit in a classroom. In Germany this even has a name: Vergangenheitsbewältigung, meaning "coming to terms with the past." Its purpose is plain: to make sure that no leader like Hitler, and no movement of similar nature, can ever rise to power in Germany (and, in practice, anywhere else).
This has gone far beyond Germany itself. Hitler and the Nazi era have become the standard comparison used by Western powers whenever they want to portray an enemy as a danger to all mankind. From Milosevic to Saddam Hussein to Ahmadinejad, the pattern has been the same: call the man a new Hitler, claim his government is the start of another Nazi Germany, and present military action as the only "responsible" course.
Keeping this comparison possible means making it illegal in much of Europe to question the official story. People have gone to prison for publishing research or even voicing opinions that go against it. Ernst Zündel is one example. In 1983, Sabina Citron, founder of the Canadian Holocaust Remembrance Association, filed a complaint against him over a 28-page pamphlet he had written in 1977 titled Did Six Million Really Die? The Ontario government soon joined the case, and Zündel faced two trials in 1985 and 1988 for "spreading false news." He brought in an international team of researchers, scientists, lawyers, and historians, putting a large body of sworn testimony and documents into the public record.
The pressure on him went beyond the courts. The Jewish Defense League, now listed as a terrorist group, threatened his life and planted a pipe bomb at his house. He tried to have the charges thrown out on free speech grounds, but the judge ruled there was "no unbridled right to say what you think." His conviction was overturned in 1992 by the Supreme Court of Canada, which said the law violated free expression.
Others were not so lucky. In 2005, British historian David Irving was arrested in Austria for statements he had made more than a decade earlier and spent over a year in prison. German chemist Germar Rudolf was jailed for publishing forensic reports that questioned certain wartime claims. In each case the message is the same: the narrative will not be challenged, and anyone who tries will pay for it.