The fact that Ukraine now defends itself means that we are in a very different situation. None of the countries Hitler annexed during the appeasement actually defended themselves, he got them for free through diplomacy. If they did defend themselves instead of joining the German side then Germany wouldn't have been threat, and there would be no need for an alliance against them and Germany wouldn't have been the biggest threat in WW2. That is the situation we see today, Ukraine is defending itself, there is no way Russia can continue invading like that, they can't afford it, so the WW2 scenario has already been averted.