20 years ago a 40MB hdd was sufficient. 20 years ago, a 486 was more than capable of running Windows 3.1 or OS2 and playing great games.

20 years on, and nothing's changed. I still need a modern spec machine to run an OS or read a word doc. My drive is still almost full. My machine is still not quie fast enough and my internet is too slow

Expectations change. Sure, in 20 years time the data we're creating now will seem like such a tiny amount, but that amount won't stay constant. The amount of data we produce each year is a proportion of available storage, not of our activity.

What I'm trying to say is that facebook have a lot of data by today's standards, but they'll also have a lot of data in 2031 by 2031's standards.

tough call. i exchanged speed for quantity with my ssd. i sort of suspect most people are going to do the same. I think it depends on how many T of video people want to hang on to.

Sure storage will get bigger and faster, but just like cpus, the transition from quantity & speed to energy efficiency will happen sooner than you're implying.