I read recently that for WW2 the german generals, or at least a very prominent one (I think it was Manstein) favoured a strategy to defeat the USSR which basically was all about encircling and destroying the armies of the Red Army one after the other until the USSR simply ran out of armies or its armed forced became crippled, and then roll in virtually unopposed and occupy the important areas of the USSR causing it to collapse, or at the very least after losing enough battles Stalin would throw the towel and be forced to negotiate a favourable peace to Germany.
Said strategy was turned down by Hitler after it became apparent that the USSR had way more armies than he had expected and that such a strategy would need a long war, so instead he focused on directly occupying the most important areas of the USSR to end the war in a quick campaign.
Let's assume either Hitler dies or is convinced and such a strategy is adopted and the German strategy for Barbarossa is all about destroying the Red Army rather than rushing to occupy it even if it means preparing for a long war.
How would this work for Germany?