If Kursk had not happened then something else definitly would have. This may be subject to debate but neither side suffered a debilitating/crushing blow at Kursk, they essentially fought one another to a standstill. At the end of the day the Germans had to remove troops from the Eastern front while the Russians had whole armies champing at the bit to get in the fight.

Once the horde was unleashed, it was going to go sosmewhere