Assuming the conventional thinkers get their will and the US attempt to supply their forces in Berlin by land, not begin the airlift. There is plenty of conflict potential here, especially as the original plan called for escalation of provcation and extraction by force of any 'stuck' convoy. Starting a shooting war is easy, and if Stalin decides not to stop it (he might, but who could possibly predict him), it will escalate quickly.
I don't think you can keep nuclear weapons out, though. They were an intregral part of US strategy in the event of war with the USSR from day 1, and the US troops doing better than expected would not stop that. After all, as of yet there is no sense of the overwhelming threat of mutual annihilation, just a vague horror of unleashing that much power. Especially absent a Soviet retaliation option, there would be absolutely no reason not to - this couldn't possible escalate further.
As to the war, that would most probably go better for the western allies than they expected. First of all, their estimates of available Soviet manpower were hugely overblown. Secondly, the late forties and early fifties were a shaky time for Stalinism, with widespread disaffection and the instruments of repression not yet fully in place everywhere. Thirdly, the USA maintained irregular emigre forces that might well prove remarkably effective, and had a ready recruitment pool in Europe.
On the other hand, the victory would most likely not be complete (who'd want to actually incvade the USSR?) and it would cause a lot of bad blood with the Eureopean allies. After all, the Soviets had gained a good deal of prestige as principal victors over Hitler, and their propagandists were milking it for all it was worth. The American propaganda offensive hadn't taken hold yet, and the later rhetorical question 'would you want to live like this' wouldn't work yet because material living conditions didn't differ much between France, Italy, Hungary and Poland in the late 40s yet. So the surprisingly hard fall the USSR takes would be seen as evidence that this was a premeditated attack by the US to further their imperialist goals by some.
