Just a little thought experiment, today.
According to a totally random page on the internet, there have been 623 million songs ever recorded.
I suspect this is somewhat high, but let's just run with it.
A typical song mp3 file is 5 megabytes in size. 5 x 623 million = 3115 million megabytes. That's then call it 3.115 million gigabytes, or 3115 terabytes.
That's a lot of data. But already, single terabyte drives are cheap at Wal-Mart, and if you've been awake for the last ten years you know that a 3115 terabyte thumb drive is something that will happen within our lifetimes...and probably not too far away. I give it ten years.
So in ten years, you could have a USB type thumb drive with all recorded music ever made on it.
I'm pretty sure this being legal would necessitate the expansion of fair use to cover all non-commercial use.