Let's start with an easy one: Will Germany be ready (war is more than cheap bodies, after all, equipment, plans, ...)? No, they won't. They've never been ready before.
Will the US help? That was a given even just 1 year ago, but now is strongly in doubt.
What will Germany's reaction be to the European states that just don't help?
What will happen to world trade? The question is who will save it, because the historical answer was of course US.
>Will the US help? That was a given even just 1 year ago, but now is strongly in doubt. With the current commander in chief, the US will do nothing except talk a lot of nonsense contradicting itself daily.
>What will happen to world trade?. World trade as we know it is done. National security interests will force strategic industries to be on-shored. New trade deals will only be made with a short list of trustworthy allies.
If Russia does attack, the US will take 1+ years to ramp up and we will take a long time before we reach Europe in large numbers. The rapid reaction forces we have are not prepared for the new way of fighting we see in Ukraine.