Ok, let's use 500 divisions, your numbers. This gives a average division slice of about 8,000 men, a bit more for the mechanized / tank corps. This means that one US / British infantry division has the equivalent manpower of about four Soviet infantry divisions or, that the Soviets are looking at parity (at best) in terms of fighting power. This does not bode well for a quick or large Soviet victory.

As for the Ardennes, the Germans attacked with three armies (6th SS, 5th Panzer and, 7th Army). The US was holding their frontage with just three divisions (106th, 28th Infantry and, 9th Armored) except in front of 6th SS on Schnee Eifel / Eisenborn Ridge area where there were much denser US divisions).
As it was, 5th Panzer in a matter of about two days was able to finally break through the 28th Infantry Division's position largely destroying this unit. An entire PANZER ARMY taking nearly 72 hours to defeat a single thinly spread US infantry division backed by a single combat command and a handful of seperate battalions!
7th Army went nowhere right from the start. They basically ran into a wreck on their southern attack axis, stalled and, then assumed a defensive role for the rest of this battle.
In the North, 6th Panzer Army made two thrusts: One onto Eisenborn Ridge where the best equipped SS panzer divisions in the German army were destroyed in less than a week in detail fighting nothing more than US infantry units. In the Loshiem Gap a single Volksgrenadier division (19th) was barely able to overcome a single US cavalry squadron in picket positions and then with the reminants of this division they managed to defeat the 106th Infantry Division that had been on the line for a total of just 7 days in their first combat posting. 6th Panzer Army was forced (note that...FORCED) to move south into the success of 19th VG due to the literal clobbering they were taking on Eisenborn ridge.
For instance, 12th VG tried to attack into positions held by the 38th Mechanized Cavalry Squadron (a small battalion sized unit). Unfortunately for the 12th this seasoned unit had wire and mines in front of their MLR which had just over 100 machinegun positions (many .50 cal) and nearly 30 mortars and a battery of 105mm guns zeroed in on their front along with dug in armored cars and light tanks. The 12th VG had whole battalions literally slaughtered (that is an accurate term) trying to assault this position.

Note further, with the exception of the 106th Infantry Division no German infantry division was able to defeat its US counterpart on its own or even in combination with a second infantry division. Yet in the reverse, many German infantry divisions were beaten soundly by single US infantry divisions in the ETO, MTO and, North Africa.
Moving to the Eastern Front, Soviet divisions did little better much of the time against German infantry divisions much as the Germans failed against the US. Only when heavily reinforced or when it was several on one could the Soviets reliably succeed.

None of this bodes well for the Red Army in a Red Star - White Star battle.