Sorry, but I don't buy it.
If you read the tactical reports, look at the overall strategic positioning, and the way the German infantry simply reacted; they fell apart.
Plus you can look at the experience level of the NCOs and jr Officers. While the German army continued to have first rate Generals, the experience of its NCOs and jr Officers was below that of earlier in the war. Both in service life and combat experience. You can easily look this up in many of the units that served against the Soviets in the offensive.
After Stalingrad, the quality of the German infantry decline. Period. It just never recovered - and after the losses in 43, it was in even worse shape.
And earlier in the war, the Germans were outnumbered by 3:1 in troops and 5:1 in tanks and didn't fall apart. In fact, they advanced.
Then look at how the Soviet's plan and operational executed this battle. Multiple opening in the front, deep armor penetrations, disruption of C&C, artillery lines, rapid follow up by infantry, and creating multiple mini-pockets rather than one large pocket. The Soviets weren't as good as the Germans in 41, but they a damn site better than the Germans in 43.
So something changed - either the Germans got worse, the Soviets got better, or both. And the numbers show it:
Exact German losses are unknown, but newer research indicates around 400,000 KIA or captured. Soviet losses were also substantial, with 180,000 killed and missing, 591,000 wounded. Of the wounded, approximately 40% return to service within 90 days, another 30% in 6 months and no information on the remaining 30%.
That loss ratio is one of the best in the war for an Allied attacking force.
Strategically, Germany totally misread the situation. The Germans believed, despite intelligence to the difference, that the attack would be in Army Group South. And they placed their best and largest concentration of mech troops there. So when the attack came, the German's literally had minimum mech reserves - the primary mech forces neutralized by Soviet misdirection to the south - and had move to a horse drawn army - as the 44 infantry division was less mobile than the 41 division. And even if Hitler had the mobile forces from the West, there is no reason to believe he would have placed them behind AGC.
And even if you could have some of the units from Italy, Norway, Holland, and France, you could never have moved all of them even if the Allied invasion didn't happen in France.
The Germans estimated that they would need at least 20-30 divisions to garrison Italy after it surrendered even if the Allies hadn't invaded - which was about what they committed in Italy.
In France, while most of the infantry division were second class - and immobile for the most part - German planning believed it needed at 60-70 division just to garrison the country. Even without an invasion.
I haven't seen studies on Holland, Belgium or Lux so can't comment.
Norway required between five and ten divisions - and even then, the resistance caused major problems especially with resource shipments south.
So your looking, at best, in transferring 10-15 divisions, and most of those wouldn't have been mobile. And, as pointed out earlier, there is no reason to believe that Hitler would not concentrated these in the south with the rest of the armor. AGC was regarded as a low priority until it fell.
Finally, Germany didn't have much of a gas stockpile at that time. Fighting a long mobile battle would be a major issue. Contingency planning in the south was extremely pessimistic for the reason. Even with the armor, no gas.
So no, even without the Allied landing, the Soviets has taken charge of the East Front. And they were going to roll into Berlin at stage of the war.