Continuing with what Guin said: German “Drang nach Osten” was geopolitically doomed to start threatening the Russian “Near Abroad,” and while Hitler thought he could take them, he was wrong.
Let’s look at models and predecessors, shall we?
Napoleon was a freaking genius, & a symbol of a sea-change in European governance. He got overextended in Russia.
The English/Yanks did conquer North America & displace the previous inhabitants, but even with technological advantages over the previously somewhat isolated North Americans,** it took centuries.** A plague across North America c. 1600 is cited as a reason the indigenous nations were conquered, but in fact the death rate among British colonists was absurdly high for generations; new infectious disease cuts both ways.
The Golden Horde conquered Russia. In the Middle Ages, with horse archers. (Though of course they just ruled, they didn’t replace the Slavs, Balts, etc.)
The British East India Company conquered India, sort of, but in almost exactly the opposite way that Hitler wanted to conquer Eastern Europe. They went native, married native women, & let the subcontinental kingdoms go along as vassal states, just giving the Indians British technology. (This is also what the Mongols, Mughals, Turks did almost everywhere they went.)
With the supremacy of German engineering in the early 20th Century, Hitler thought he had a chance at technological dominance to medieval Mongols. But his race theory may have worked against him here. The German academy c. 1900 succeeded in part because, like the medieval Mongols, it was cosmopolitan; not because of the nationalist backlash of which Hitler was the zenith & climax. Long-term, Hitler’s nationalism & Race Theory allowed the French & English (who had had their own dippy nationalists) to appear to be enlightened cosmopolitans, & paint the Germans as self-important nationalist buffoons.
OK, so say you’re not Hitler, & you’re not pinning all your hopes on exterminating Balts, Slavs, & Jews and repopulating the East with your own people in your own lifetime (which Hitler knew was hard as hell & took extreme willpower; he was trying to get it done while he was alive to make sure it even happened). Do you have a chance to wipe out the Commies?
Ha! No. Because like Napoleon before them, the Marxists represented a new governmental order. They were the hot new thing, the Fascists were a conservative-backed alternative pinned on dubious racial theory & created to oppose the revolutionary movement with the actual mass appeal.
The Internationale gave people a new, apparently transcendent, civic religion, for the whole world. Fascism & Nazionalsozialismus lost strength with every border they crossed. And international capitalism wasn’t going to rally the people; Marxism had been invented in response to capitalism’s manifold flaws, which had spurred revolutions generations earlier, in the 1840’s! Capitalism didn’t know how to answer Marx yet. Although the social democracy in post-Bismarck Germany was the start of an answer, the right still backed Fascists & Nazis to keep the Reds down.
These days, we can mix and match neoliberalism & social democracy & laugh at old-fashioned Marxists and protectionists. But in 1935, the USSR was still apparently viable–and the Iron Curtain wasn’t really up yet. Fighting communism meant fighting your own people who thought it looked like a good thing.
So, yes, a moderate national leader could have done all right domestically. Obviously.
That said, and here I am guessing: A crusader against communism, if he moved east militarily, probably would have failed to make much dent in the Russian sphere of influence, & could have wrecked his own country economically by pushing too hard. He could have avoided the crushing ruin Hitler brought Deutschland by being less of a fanatic. I’m not sure that a committed anti-Communist that embraced cosmopolitanism & scientific progress would have been more politically successful than Hitler; I don’t think he could have conquered Russia in any case.