The Soviet Union collapsed because the economic system itself
was unstable, unreliable, and frankly unnatural.
Nazi Germany however was somewhat freer economically, more
capitalistic that is, so it wouldn't have collapsed from that.
The Nazi empire would've collapsed simply because they would've
had to rule over too large an empire, including most of Europe,
as well as much of N.Africa, C.Asia, SW Asia (Mid-East), and other
parts, not because they wanted to (though they might have), but
because they had to, to prevent these areas from falling under
US influence (I am assuming the Germans merely defeat, but don't
conquer the US, subsequently having a Cold War with it).
There is no way such a, empire could be maintained, both in
terms of money, and in terms of man-power.
I wish to disagree with those who say "I wouldn't be alive today,
because my grand-parents..." etc.... I disagree because I
don't think the Germans would've just gone around getting rid of
every person who wasn't Aryan. Maybe from Greater Germany, but
not from Europe as a whole.
To get rid of all non-Aryans from Europe means getting rid of
most of Europe (Italians, Greeks, Slavs, Baltics, French, Irish,
etc...).
As far as people within Greater Germany who weren't Aryan, I
don't think they would've killed them. I think deportation would've
been more likely. Even non-Europeans would've been at the most
just deported. The Nazi's wanted a racially-pure Greater Germany,
that's all, how that came about (deprotation or killing) didn't matter
as much. They didn't care as much about the rest of the continent.