Optane was never going to reach Flash levels of density. It was always in that awkward zone between DDR4 and Flash. Slower than DDR4 but faster than Flash. More dense than DDR4 but less dense than Flash.

It was a failure of marketing and building. Today's computers use a team of DRAM (like DDR5) and Flash. (GPU-ram like HBM or GDDR6 are still DRAM fundamentally).