There's a whole host of premises packaged with that loaded question that I already disagree with, such as the notion that only the existence of NATO posed a credible deterrence post-WW2 to a Soviet invasion of Central Europe.
There are always alternative paths to achieving things, so yes a Europe without NATO could have developed.
But you do agree a military deterrence of some form was necessary to prevent Soviet expansion given they had already demonstrated, on multiple occasions, a willingness to forcibly conquer territory to expand their sphere of influence?
What do you think this would have looked like though? If the US had simply washed their hands of Europe after WW2 and let Britain, France and the USSR fight it out among themselves? Do you think this is more likely to have produced a stable Europe? Personally I'd say it would be far less likely.
No one trusted each other. Without the US to help impose some kind of settlement with their economic and military leverage, as well as help rebuild economies and defences what would happen to Germany?
With France and Britain having to rebuild their economies while rebuilding their militaries to counter the Soviet threat (and potential German threat), there would be more chance of extremism.
You also have a balance of power in Europe that would be far more delicate which is not a great recipe for stability.
If anything, it was NATO that produced the motivation for the USSR to advance its sphere of influence by locking them out of those areas and facilitating American military and economic dominance over half of Europe.
Or the expansionism of the USSR produced the motivation for the Marshall Plan to prevent more of Europe being dominated by the Soviet Union.
Both sides perceived threats.
The Warzaw Pact and COMECON both were reactions to the Marshall Plan and the foundation of NATO, and probably wouldn't have happened if the Allies had managed to co-operate after the common threat of Nazi Germany was gone - an unrealistic pipedream, certainly, but an interesting hypothetical to think through just how much geopolitics were influenced by the antagonism of West vs. USSR, an antagonism that very much preceded any supposed USSR "motivation" to invade Europe (the first and last time the USSR half-seriously attempted such a feat was when Trotzky was still running the Red Army).
The antagonism was basically inherent in the 2 ideologies. "Socialism in one country" rather than global revolution was only due to the failure of the latter to materialise.
If the Soviets had been militarily dominant post WW1, it is far less likely they would have changed tack in this way. If other nations had had the military ability to prevent it without significant costs, it's unlikely they would have allowed the Soviet regime to be established in the first place.
There was no 'good' solution post WW2, but, imo, without the US, Europe would have been far more volatile, and far less likely to develop into relatively peaceful and stable nations.
At least with US intervention the 2 blocs were relatively stable and the 'question' of Germany had probably its best possible solution.
What do you think was both realistic and would have had a good chance of resulting in a better outcome?