What happens once the size goes beyond 1TB, or beyond the biggest HD? what happens when you can't fit the blocksize in a regular HDs? Can you run 3/4 of the blockchain then the remaining 1/4 part in another HD?
LVM will do the trick. Anyone can build a virtual 2TB HDD from 2 hdd 1TB cap.
It's not a HDD cap problem, it's how btc works.