I think it's fair to say that Optane was not merely "not a smashing success" but was completely uneconomical. Intel was essentially using Optane products as loss leaders to promote platform lock-in, and had limited uptake. Micron made only the smallest token attempt to bring 3D XPoint to market before bailing. Clearly neither partner saw a way forward to reduce the costs drastically to make it competitive as a high-volume product.