A personality change would be required, or else Hitler would be either edged out by more sane communists (and, given the SU's influence, also ones more loyal to Stalin - Thälmann fits both, for that matter) or would end up implementing a very, uh... national kind of "socialism". Hitler was already a raging antisemite (according to Mein Kampf) even before the war, in Vienna. He dodged the A-H draft because he thought the KuK Army was too ethnically diverse. He was already a hardline German nationalist in his school years. I think that this needs an early childhood POD, after which the butterflies can make anything possible, but other than that, it's ASB. Especially because he couldn't just make his way to the top of the KPD somehow and then keep his antisemitism and anti-Slavism bottled up - the communists wouldn't have been wooed by personal charisma, and theory discussions during party congresses would quickly have revealed Hitler as a crappy Marxist who shouldn't be trusted.
