It doesn't have to be consumer hardware to be economically viable. I can imagine something like this replacing or complementing tape storage at data centers. We already have hard drives filled with gas for dust-proofing. For archival storage it does not have to be fast (in terms of latency) it just needs to be reliable with high data density.

Hard drives where the size of a car decades ago, we could now have archival storage of the same physical size that can hold petabytes (just guessing, didn't do the actual math).

The question is how much are readers. If I have to take my data to my local strip mall to write my datacube, but this data cube can be read with a much cheaper reader that I can reasonably believe will be available in 40 years, I could see that as being viable.