Odds are the Soviets overruns NATO lines in Germany with the only question being how quickly it goes. Though the possibility of NATO holding off the Red Army is hardly out of the question, even if it is the less likely of the two possibilities. Either way, loser likely breaks out the nukes. Things escalate from there.
Tensions rise along the FRG and the soviet occupied zone are intense and the USSR start a war there are no nukes involved for fear of total annihilation French Italian Benelux and British soldiers hold and make a steady retreat towards the fortified Rhine once at the a similar time to WW1 begins as forts are built and trenches are dug the Russians arent able to penetrate the fortifications even with tanks and planes any attempts to cross are foiled and heavy AA guns are set up behind to prevent para drops British american and Canadian navy's block the black sea and other areas any attempts to invade Alaska are foiled as well and from the sea to Switzerland theres trenches how does this continue?
Holding the Rhine should the Soviets reach it? That isn't likely to happen. The West German armies would have been wiped out trying to hold forward and the American armies might have been encircled by the Soviets northern thrust while the BOAR is, at best, attrited to pieces.
Also when historians make the observation that WW3 would be like WW1 they do so as an analogy for a technological and tactical stalemate that boils down to whose logistics and/or morale breaks down first... they don't mean
literal trench warfare.
Well considering that the Soviets had let a system as critical to national defense as their Nuclear early warning system decay to the point that it went haywire and nearly triggered a full Nuclear exchange, yeah, of say they were a shell of their former selves. Now granted, NATO didn't realize this at the time.
Erm... no? Soviet issues were certainly mounting in 1983, but they were still together enough that the odds favored them. I also don't get where you believe the Soviet nuclear EW system decayed or went haywire in 1983: the Able Archer incident was a function of human paranoia in the leadership, not issues with their EW net, and Petrov's case was that of an isolated false-positive that happened a number of times on both sides of the iron curtain throughout the Cold War.