The difference between now and then is nukes. In retrospect, shutting down Hitler early on seems like a no-brainer. Add nuclear weapons into the equation--and it's a whole lot different.
The other difference is that the Russian military is proving inept at logistics and coordination, which is required to make good use of their advanced weapons. There is no doubt that they
have some devastating non-nuclear capabilities, but they're already somewhat winded just trying to take down Ukraine. Unless other incursions are about 10x friendlier than Ukraine, I don't
see how they hold it while expanding elsewhere. I also suspect that China, which is run by far more intelligent people, has probably warned Russia that it forbids use of nukes. China wants to
be rich and influential, and nuclear war would ruin that worldview. At the same time, I suspect Russia doesn't want to get too close to China, as Putin views himself as the world's top dog.
China's economy dwarfs Russia's, so Putin would be second fiddle in any imagined alliance.
But what do I know. Let me not suffer the fate of the DUmmy and believe my opinion has validity.