The problem is optane wasn't as fast as DRAM, nor as cheap as disk. So you still needed the conceptual split anyway, and there wasn't a compelling reason to really use it (OK, I can get a lot of RAM but it's 1/10th the speed of my normal RAM, which will kill both memory latency and memory bandwidth limited applications, which is basically any workload which wants lots of RAM. Or I can get super fast persistent storage with high durability but much higher cost, which basically makes it good for a persistent cache but not that much else, considering SSDs are now similarly fast even though their durability is not as good). It wasn't sunk by a stuck-in-the-mud way of thinking about memory versus disk, it was sunk because the tech never got good enough to actually achieve their ambitions.