Both Joseph and CT lawyer
Although lawyer explained the situation in Connecticut main point here is that everyone practically has forgotten about the Nusach Ari non chabad shuls. There were many people who lived near first Chabad Rebbe ztl who accepted his Nusach but did not become Chassidic. They developed what was called Nusach Ari synagogues and although many Chassidim davened by them, the bulk were not Chassidic.These synagogues flourished in Europe through the previous Jewish neighborhoods ( Brownsville,Old Crown Heights,East New York etc) in America,and, for various reasons, could not be reestablished in the New ones. Still, there are many people left who daven Nusach Ari but that’s all. Interestingly,one of the last to either change Nusach or close was the one in Crown Heights which obviously eventually became Chabad.