Still the forces concentrated in France were quite significant. In the entire Normandy campaign, no fewer than 400.000 German soldiers were lost to all causes. Over 500.000 troops retreated across the Rhine. That's almost 1 million men...
My guess is that , with the western flank secured (ie. some kind of certainty no invasion would occur), the Russians would have an extremely hard battle to fight. Remember the Red Army took 12 months to get from Kursk to Kiev (500km).
By late 1944, the Russians were running short on men. They also had mounting ressuply problems, which forced them to wait for weeks on end.
With 1 million more Germans in front of them, it may have been possible that the front line would have stabilised somewhere in present day Ukraine (which is again a battlefield...)
You numbers are too smal after primary sources.
After primary sources there were 1,4 million german soldiers at the west and from the required strength of the units roundabout the half of the whole fighting power of the Wehrmacht
Also most of the elite and fresh german Panzer Divisions were at the west.
1., 2.,9.,10 and 12 SS Panzer Divisions and the 2., 21., 116 and Panzerlehr Division.
I have no doubt that sooner or later the Red Army had won, but the war with all these troops at the east had continued much longer.
Sorry, late reply
Many elite divisions were deployed in the East: 3 Totenkopf, 5 Viking, 1 Herman Goering, and others.
The important thing to observe is that the eastern divisions were more heavily armed and equipped.
Many divisions that were caught during the Normandy assault, and later during operation Market Garden, were actualy in the area for rest and refit...
The only full strength
division sent especialy for the Normandy assault was Panzer Lehr.
This is why I would estimate the maximum number of German combatants
at under 1 million in June 1944 in France.