Seeing as its raison d'etre no longer existed, NATO gets disbanded in 1992.
The raison d'entre was "To keep the Americans in, the Russians out, and the Germans down". That formula still works following 1992.
More seriously, the extension of the US nuclear umbrella over much of Europe through NATO is the greatest anti-proliferation policy ever enacted by the western powers. NATO keeps the European membership of the nuclear club limited to the US, UK, France and Russia.
If you were the President of Poland (or another former Warsaw Pact nation) as a neutral/non-aligned country still next to Russia, would you forgo developing a nuclear arsenal?