Today it is not uncommon people have 2 TB with minority of nerds having 8 TB/16 TB.
It is not unreasonable to expect in 6 years replace the terms in the sentence above with 10 TB, 50 TB/100 TB. This is what I meant. Sorry for confussion if you thought average 55 TB in 6 years.
In theory, Bitcoin will scale even to visa level txs and beyond based solely on technological advances. The probability of that happening is actually 100% unless we somehow fail as a civilization, have a 3rd world war, a meteor hits earth etc etc. Otherwise, in 20-30-40 years, a 10gb block will be the equivalent of a 1mb one. It's like PCs went from kilobytes of ram, to megabytes, to gigabytes and home connections went from a few bytes per second to megabytes per second.
There are however some issues on the hardware market. Issues like the fact that CPUs are not advancing the way they should, given that AMD is lagging and Intel doesn't have to push too much (a 9 year old quad core is currently cheaper and quite competitive with low end chips of today by AMD and Intel. This would be impossible between, say, 1991 of a 486 @ 50ΜHz and 2000 with a low end Celeron or K6 running 300-500 MHz)
Optical drives are also stagnant. If someone saw the CD->DVD progression of the 90s, where DVDs had capacity near what a hard disk had at the time (in '95 a CD was ~700mb and a disk was ~500-800mb, in 98-99 a disk was ~4-10GB and the DVD was 4-8GB) you'd expect we would have >1TB optical discs right now but they are buried in some lab, despite having read about such advances multiple times. We didn't use to have ...HDDs for "storage", we had floppies, then CDs, then DVDs... now we have HDDs - which in a way is artificial demand for HDDs and still HDDs don't offer cost effective ways of storage.
I bought a WDC 1TB 7200rpm (blue / ealx sata2) around 5 years ago for ~62 euro and its price is not much different currently (59 euro). In the 90s, if I paid the same money I paid on my wdc 80mb in 92, I would get a Fireball of 6.4
GB in 97.
If manufacturers were running full speed we'd be seeing a whole different market. Now with the content stored online, you download a movie, see it, erase it. 10-15 years ago, people hoarded videos etc and stacked them in DVDs, etc. Then they run out of space and started buying HDDs and external HDDs. Then they stopped hoarding, just downloaded and erased. So no motive for HDD manufacturers to go dramatically lower on $/GB, plus they have a cartel nowadays that works as inefficiently as the cpu one.
TLDR: While it's a mathematical certainty that over a long-enough timeline bitcoin will scale as technology evolves, in the short-to-mid term, we have to face some market anomalies that create an artificial slowdown in significant (and affordable) increases of cpu power and hdd storage space.