>>17904603 (OP)
No. Without Allied assistance the Germans obviously would have won. Look how far they advanced, after already being at war with (and under blockade from) the British Empire for two years (and a cold war with the US for at least a year through things like lend lease). And they still almost made it to Moscow, whilst a portion of their army was spread from places like North Africa to garrisoning places like Norway and France.
Not a wehraboo, but the reality is a 1v1 war between the 3rd Reich and post purge USSR, no Western assistance whatsoever = German victory.
Once Hitler controls from the Rhine to the Urals, including the Caucus oil, he's undefeatable. That doesn't mean he'll take over the world; he'd still have no means of realistically conquering the USA. Or even really Britain, as Germany in this scenario would have pumped almost everything into it army and air force since a world beating navy wouldn't be much use on the steppe. But he would be in a position where the West couldn't have successfully taken him out either.
So we'd end up with a Cold War again, but this time with a victorious Hitler as the "other guy", rather than Stalin. Which means Hitler inevitably gets nukes. Which means the world ends.