I spent a bit of time catching up on this thread, wow…
My two nanos below as it pertains to the cost of HD storage and where the tech is going… its all good for Autonomi Network. 
Just sayin, all of us might want to consider the technology of storage keeping ‘data forever’ is becoming capacity dense with faster access, more rapidly then most of us realize, given the current HD tech is really not optimized to last a life time of say 100 years, and the current software speed of access is only 20% of the what the actual HD media speed is capable of in terms of WRITE speeds(Uploads). Read speeds(playback) are just fine even on PCIe Gen4 with your HDs connected via an X4 lane.
There is good news coming as Really low cost Shingled Media Record SMR HDs are just starting to show up. WDC and Seagate originally thought this tech would be slow, 4X slower than current CMR (Common Media Record) HDs we all use today, but these vendors have been proved otherwise by new and continuing software improvements to speed the Flash Translation Layer that now sees the speed the same for SMR as it is for today’s CMR Common Media Record HDs we all use, where SMR promises much greater capacity at at least 35% lower cost this year, so that part of the market is changing fast.
With the above advancements in SDR, we can all expect to change the storage type utilitzed for ‘store for ever’ every 5-10 years because HD media does wear out, changing that old tech to much lower cost read/write performant SMR HDs (keeps your Autonomi safenodes from getting shunned for being slow to respond to connections becaue HDs are the speed bottleneck in any system, leaving more CPU clock to do relays of copies, etc…,).
So expect your curent HD tech to replaced by technology which is 4X faster (3 to 5 years) which will be at least 4X more capacity dense with typically 2X to 4X better price performance emerging in the next few years.
Given the past historic trendline for price/performance of HD storage,
the HD price/perforrmance and capacity set of changes will occur across the Autonomi Network sporadically over time in the next few years and be massively parallel, which means the ‘cost to store for ever’ will drop as that denser capacity is added in larger amounts collectively over time to the Autonomi Network.
My own observations about physical storage units tells me when they get built they fill up fast especially when the annual or 2,3 or five year charge rate is low.
Why? It’s human nature to hoard everything, IF there is enough cheap space to do it. We humans like our stuff around, even from child hood. 
Autonomi Network won’t be any different, with us humans wanting to save pictures and videos, and ebooks etc,
without the hassle of upgrading their own hardware to expand capacity or move their stuff before their own storage breaks (and it will break).
So provided Autonomi Network is conventient, easy to use and low cost, regardless from which device or system you are uploading that stuff to be stored forever, my prediction is humans,
should they become aware of Autonomi Network (the big and real challenge) and,
find it easy to adopt(with the convenience and low cost mentioned above),
a big mass of online humans will start uploading lots of their stuff to the Autonomi Network.
It will be a Tsunami not seed in the digital world, IF we all work together to get the covenience, easy and low cost thing right.
The economics of new SMR HD storage hardware will help too at some point in the near future…
Heck even flash NVME tech price/performance AND capacity is falling really fast in price and that will help some too.
The other factor is PCIe Gen5 has doubled the bus speed and is now shipping, which means the X4 lane speed to the HD has doubled.
the latter Gen5 to be replaced by a doubling of bus speed again with PCIe Gen6 in just two years!
ant that makes the X4 lane connected to your Hard Disk Drive also go 4X faster within 3 years, from what it is today to make the cheap SMR HDs with tons of capacity, lower the overall cost of storage by at least 4X in the next 2 to 3 years when uploading to same on the Autonomi Network.
That means Autonomi Clients paying once to store their vast libraries long play Videos in 1024/2K/4K format and one day in 8K format for very little cost with performant play(read) speed, will become a reality, faster than most of think it will.
Autonomi Network is gonna be great if we get this right, working together!