Would Europe have survived

[mapuc]

In our US-Politics thread Shawdowblade wrote in an answer following

"In reality America was saving Europe several times already. I thought people playing Silent Hunter would know it well "

This made me wonder-If USA had stayed out from both World Wars, would Europe have survived Germany and its allied ?

Now the history tells us how Japan attacked USA Dec. 7 1941 and thereby dragging US into the war.

What if USA only fought Japan in a single war and stayed out of Europe ?

I think the Second world war would continue past 1950 and ends with a nuclear exchange between UK and Russia against Germany.

Notice: I do not have enough knowledge about the first world war-I therefore didn't make any prediction on how this war could end.

Markus