Costs
So $180 for 300GB is 60 cents per GB. Given that flash storage (retail) is not much more than twice that and prices are declining rapidy, then what is the future of this technology? I'm not sure what the longevity of flash storage is, but random read access speed is vastly higher. Also some form of archival flash storage would not require drives at $18,000 a time. It's not there yet, but in two or three years time?
To make holographic disks make sense, then the capacity will have to be much higher and the costs a lot lower.
Also, any outfit that relied on a 50 year media lifetime without regular refreshes is running a major risk. Experience shows that digital media often has a much shorter lifetime than originally advertised.