US Deputy Assistant Secretary of Defence Morton Halperin said:
The NATO doctrine is that we will fight with conventional forces until we are losing, then we will fight with tactical weapons until we are losing, and then we will blow up the world.
It feels a bit unfair to use that quote, as Halperin was never all that senior, but still it's not entirely wrong, and really does illustrate the point - neither NATO nor the Warsaw Pact expects that there really can be a conventional war in Europe, so it sort of has to be a damp squib affair, where the Warsaw Pact forces do not make significant gains towards Hamburg or through the Fulda Gap before giving up on the whole thing as a bit of a waste of time - probably because USSR internal division precluded the use of WMDs at the strategic level, and the giving of operational control of WMDs at the tactical level to the military. So figure less than two weeks, maybe only one, between the commencement of hostilities and a ceasefire in place.
A short war actually diminishes the US' role in it, as the return of forces to Germany still takes some time no matter how well planned. So we're looking at a prospect where the USSR doesn't break through the standing forces (3 German, 2 US, 1 British, 1 Dutch, and 1 Belgian corps), where the reinforcements that plug the gaps are 2 French corps in the main, and the US narrative probably focuses on the war-winning impact of the USAF.
Tough for the Soviet Union not to go to pieces, I think, though the level of casualties and the economic disruption of the war are key to how orderly the transition from a Union to a bunch of pretty disorganised oligarchies is.
The Warsaw Pact is... tricky. It's very much up in the air how East Germany goes - whether a failed war will be the cause of a populist uprising, and whether Honecker tries to put it down, and if so whether his regime is successful. You could get an orderly Soviet withdrawal to the GDR at which point it is inj place to put down the East with a pretty horrific toll, or if the lid stays on until the Soviets and Poles have withdrawn then it does rather beg for West German intervention in support of the insurrection... and indeed whether that support ends at the Poland-GDR border or the Leopards continue to roll further east in a sort of anti-Barbarossa with legitimately-popular support until they get to the ethnically-Russian bits of the Baltics. Okay, that bit's pretty fanciful; only in the worst case of full-on RCWII does the RKKA not remain in force in the Baltic states until NATO gives up on liberating them. It's probably a safe assumption that any "stabilisation" moves eastwards will stop short of resuming combat against first-line Soviet formations, so wherever the motor-rifle divisions park, the Bundeswehr will laager up at least 20 miles further west.
In Western Europe as a whole, leftist sympathies are in for a beating at the ballot box. Some strongly Marxist/communist types - from the communist parties, from trade union, and from academia - will probably have been detained for the duration of hostilities, and there will be lingering issues there in many cases from the internees faced with public hostility.
As US forces stream towards Europe even after the ceasefire "just in case", there will be a temptation for Reagan to take advantage of the opportunity and have a Gulf of Tonkin moment in the Gulf of Sidra, and unleash the Sixth Fleet and the USMC on Muammar Gadaffi, though the spectre of Scud-Bs dropping chemical weapons on Naples may restrain the enthusiasm for that venture.
US politics - if the war's not that big, relatively speaking, and ends without Abrams rolling into Russia proper, there's a danger to the GOP that it won't be a big
enough victory, particularly if it can be spun that Reagan's jingoism ("
we start bombing in five minutes...") can be blamed for spurring the Soviets into attacking. That's a pretty speculative point, though - a few good speeches one way or the other and the
zeitgeist will find a tipping point, as it's clear to everyone that things were very very close to Vera Lynn singing "We'll Meet Again" in the end-sequence to
Dr. Strangelove. A lot depends on the Democrats - Dukakis was the sort of candidate to snatch defeat from the jaws of victory, but a number of the other candidates might do better, maybe Gore, Simon or Gephardt, or if the disruption of the war means that Gary Hart can either keep his pants on or keep his affair secret.