How long could Nazi Germany delay its defeat?

[Johnrankins]

One thing that always amazes me is that British+Empire actually fielded more troops (17.8m) than USA (16.3m, of which around 4.2m were Navy so I assume fighting Japan) ...
... and that Germany (18.2m) somehow thought they could win against the Soviets (34.5m) and Brits (17.8m) and USA (12m), odds of more than 3:1 against

The British Empire entered the war earlier and had a much larger population. India alone had far more people in it than the US and fielded the largest all volunteer army in history.

 

[The Tai-Pan]

But if Hitler ordered guerilla warfare to be used, I would see this war taking in up to early 1950s in best case scenario and be the most devastated country on ww2

The Allies would fall on them like a ton of bricks.

 

[Garrison]

But if Hitler ordered guerilla warfare to be used, I would see this war taking in up to early 1950s in best case scenario and be the most devastated country on ww2

But this is the 1940's with D-notices and no 24 hour rolling news. As the full scale of Nazi's atrocities became apparent no one will object to the most brutally repressive tactics being used, not to mention that guerrilla movements rarely last long without an external source of support.

 

[Look More Closely Later]

Problem is that requires your new leaders to be three things:

1). in a position of authority in the Nazi regime to take power in this way and keep it

2). Be able to recognise in 1943 Germany's going to lose in 1945 so completely

3). be capable/willing to give up everything they gained since 1938/1939 (and remain in power while ordering it)

They're basically a Notzi unicorn. The Nazi/German government and power structures had by this point spent a decade creating a situation where any of the above would be weeded out or side-lined as individuals let alone as a group.

2) is the real problem on your list to my mind. The earlier they decide to quit, the greater their chances as I see it of surviving (not least because the earlier they quit, the more Allied casualties even the Allies are going to see, will end up spared.) The problem is, the earlier it is, the easier it is for Nazis (from their abominable racist perspective) to believe that the wonder-weapons will defeat the British and the Russians will be stupid thuggish sub humans who will lose to Teutonic might and the Americans can somehow just be kept on the other side of the Atlantic or at least the Alps/the Mediterranean.

 

[Look More Closely Later]

One thing that always amazes me is that British+Empire actually fielded more troops (17.8m) than USA (16.3m, of which around 4.2m were Navy so I assume fighting Japan) ...
... and that Germany (18.2m) somehow thought they could win against the Soviets (34.5m) and Brits (17.8m) and USA (12m), odds of more than 3:1 against

Unfortunately the British also fielded some of the most incompetent, muddle-headed, or over-promoted commanders of the war as well. (e.g. Percival, Mountbatten, 'Bomber Harris'...)
And then there was the whole tank fiasco.

 

[HexWargamer]

Unfortunately the British also fielded some of the most incompetent, muddle-headed, or over-promoted commanders of the war as well. (e.g. Percival, Mountbatten, 'Bomber Harris'...)
And then there was the whole tank fiasco.

and yet, despite all those handicaps, somehow, they 'won' (or at least didn't loose) ..
Which says (to me) that there's little way for the Nazi's to do any better i.e the British are already as bad as they can be ...
... there are, perhaps, some tweaks that let the Nazi's last longer , but the big changes means they are no longer Nazi's ..
[here's one tweak - the 4 rotor Enigma gets introduced earlier ... and then some-one points out that the cost of the machine with it's entry ring, the 4 swappable rotors and the 'reflection' ring is the same as a real 6 rotor machine, so they get rid of the complex 'reflection' bits (which was what prevented a character encrypting to itself and is the flaw that allows the machine to be cracked) i.e. they introduce a version that can't** be cracked]
**EDIT with the technology of the time and assuming they use it correctly (i.e. no insane encrypt the 'start key' twice .. or use the same start key twice wit the same day settings

NB. don't get me started on American tanks (USA SHOULD have been churning out Sherman's in 1940, what they had was that abomination the M3 Grant, which is essentially a knock off Char B designed in the 1920's (ie. the early one with the thin armour, not the one that the French eventually built after 15 years of ditherrring)