Caveat - this is conjecture on my part, not the official or unofficial perspective of my employer. It's just a set of theories I have based on my reading of well documented historical events and circumstances.
My guess is that we would have seen limited nuke use if conventional weapons (including really nasty ones like mines and cluster munitions) were insufficient to slow the advance long enough for reinforcements to arrive from the US and other mobilized NATO nations.
Basically if NATO started losing a ground war in Europe, tactical nukes or other WMD could have been used to slow the advance long enough for the Soviet supply chains to come to a halt. An army can only run forward for a few days before it needs to stop for beans bullets and gas. Tactical nuke use would have halted the war in about a week, especially if they were used only on territory that was recently taken by the Soviets, on lines of communication and supply. Make everyone fight in an NBC environment and slow resupply to a crawl due to contamination issues, and the war simply ends in a week. And no global retaliatory strike occurs because the territory being nuked was NATO to begin with. An ugly but most likely effective and "least cost" solution, in terms of loss of human life, in spite of the WMD use.
Nuke and then slime a freeway or supply chokepoint, and civilians away from the immediate kill zone still have a chance to flee. But that LOC is compromised for resupply for days, slowing the advance which saves other lives. A tradeoff.
That's one realistic and plausible scenario... There are others. But supply and realistic limits on effective combat operations in an NBC environment could be decisive no matter who uses them first, even given the overwhelming numbers of troops and weapons on the Soviet side. The bottom line is that the NATO chiefs and national leaders had the starting argument that Europe would simply not be overrun, under any circumstances. There was never a question whether or not NATO had the military power to back that up, the only question was if the various national command structures had the willpower to do what was necessary when the time came to take irrevocable decisive action.
Then again, it might not have come to that. The A-10, F-111, and various other aircraft had some very specialized weapons designed to do nothing but take out Soviet vehicles, including their best armor. Liberal use of aerial delivered mines and cluster munitions may have been able to slow the advance enough that a massive amount of airpower from the states could arrive "in time", in about 48 hrs, to finish the job with conventional weapons only. But if the advance couldn't be slowed enough, I think we'd have seen limited authorization for tac nukes or other WMD designed to slow the advance rather than halt it, in the hopes that limited use on non-soviet territory would not provoke a global retaliatory nuke strike.
Heck, why do you think many Europeans protested the presence of nukes and other WMD so vehemently? They knew damn well those weapons could have been used on NATO soil. War is hell and many civilians simply don't want to win at that cost.
Remember, it was stated numerous times that tactical WMD use was always an option in a European theater war. And we didn't really start dismantling that capability until well after the cold war ended. And lest we forget, there are still NATO nukes on NATO soil, and the old mutual defense obligations have not expired.
