Well, it was only a theoretical outcome. But I must point out, that in January 1945 the output of weapons in German factories was more than four times that in 1940. So bombing was not ruining their industry.
Agreed, mate. They were turning out far more than they were in 1940, but tanks, planes, guns etc, not to mention men, were being destroyed, just on the Eastern Front, at a rate far exceeding that in 1940. And that, they couldn't keep up with. Even with the forced labour and the moving of vital installations underground etc, they still couldn't keep the flow of 'decent' weapons and equipment to anything more than a 'trickle'. And of course, there was the fuel problem. The failure of D-Day wouldn't have changed that in any way.
By June '44, the Russians had pushed to Poland. They had their T34's in HUGE numbers, which were more than a match for anything less than a Panther or Tiger (which were in such short supply that they were being madly shuffled from one area of the front to another, just to try and plug up or reinforce areas which were breaking or weakening). So there was absolutely no hope of the Germans being able to get at any oil fields or reserves behind the Russian advance. And there really wasn't any oil anywhere else within reach.
Anyway, after all is said and done, post mortems and 'what if's" aside, Hitler made his 'fatal' mistakes years before D-Day.
The majority of high ranking German Oficers, ministers etc, knew by JUne 1944 that it was simply a matter of time. Many knew even before that.
So, in the nutshell, even if D-Day had failed, I can't see how Germany could have survived for much longer than she did anyway. Maybe another year (just my unqualified 'guestimation').
However, I agree the political & geographical situation in Europe would certainly have been a different one from that which did emerge.
In fact, I think, had the Russians totally overrun Germany and 'absorbed ' it, there may well not have been a place called Germany afterwards. ;D
