Originally Posted by Doppleganger
Actually I had the T34 in mind when I wrote that as it was pretty basic in terms of design and finished product - the Panzer IV was made like a swiss watch by comparison.
Well, to be honest Germany was pretty much on its last hurrah when Guderian suggested that all tank production be focused on the Panzer IV. Kursk was the last throw of the dice in the East and it never had a great chance to succeed IMO. After Kursk it was defence all the way and Germany needed quantity over quality by then, something that the Red Army had done from necessity (and perhaps design) years ago. The Panzer IV wouldn't have compared very well with the IS-2 and especially the IS-3 and M-26 Pershing but by the time they were deployed it was basically all over anyway.
My point is that the PZ-IV was pretty much at the end of its life but retooling plants to make its successor was never really going to be an option given the conditions even in late 1943 therefore the best use of materials was to extend the chassis life of the Pz-IV by converting it to the Jagdpanzer-IV, in doing so you are up gunning and armouring the PZ-IV, reducing the cost of production and material usage for the loss of the turret but as a defensive vehicle I do not believe that is a massive loss.
To my mind the Jagdpanzer-IV was the best vehicle to produce in massive numbers after Kursk, back this up by either devoting all your effort to ironing out the problems with the Panther or even continuing the design of the Tiger I (I imagine they could have sloped the armour a bit in areas reducing its weight without reducing its effectiveness).
Also I highly doubt German planning was based around losing the war in early 1945 therefore they had to design their production plans for operations as far forward as 1946-47, in fact I think it is Antony Beevor's Berlin the Downfall that quotes Speers production plans for 1946.