Russia simply doesn't have the numbers to fight such a war, and it most certainly doesn't have the conventional weapons or infrastructure to quickly make them.
NATO doesn't have the forces in being for such a large front war either, but they would fair much better than the Russians on the expanses of Poland and Belarus, where the large tank battles would rage. In the south, Hungary, Romania, and Bulgaria are sharp hilled geography sprinkled with tiber patches and pillbox-like houses. Ivan would have a very tough go of it, against those peoples, where willingness to fight would make all the difference. Ivan would also have to contend with some really pissed off Ukrainians overlooking his supply lines.
The Baltic states might get taken before they could be protected, but I wouldn't count Sweden and Finland out of the game, just because they aren't NATO. And China might just decide it was time to annex a good sized chuck of Siberia, while everything was sorting out in the west.
Once again, the Poles would do a lot of the fighting and the dying.
Russian agents could incite the muslims in Europe to go bananas against the rest of the population before it is all over.
You’re right.
I do think though that Putin has grand ambitions and he is likely planning on some kind of conquest.
So, he’s making an unconventional war via incremental ‘annexations.’ Unlike Hitler he won’t use upfront war methods, but they will be far more Byzantine. Something is up with him and you can practically hear the buzzing going on as he racks his brain to figure out how to win, I know that much.