I don't think there was economic in massive nuclear bombing, NWs were and are mostly psychological. E.g. the absense of nuclear bombs didn't stop "even" US from grilling Tokyo urban areas with incendiaries with total death toll equal to those in Hiroshima + Nagasaki. Yeah, it could be done much faster with modern delivery systems, but we also have lots of effective non-nuclear mass- and precise-destruction weapons today.

In the end, though nazis didn't value non-arial lives, they were no idiots. Why would they destroy cities and pollute areas supposed to be the part of Reich? The end of the world is both hard and unprofitable. "Nazis would" is a scary tale nicely covering the actual face of war that always remained the same.

What is really scary today is that some countries develop supreme air/space control systems, so those in the club become immune to any sort of dialog.