I've seen the tech side work. I worked at Fermilab on the USCMS side of the LHC for data taking; we had 5PB of spinning disk and tens of PB of tape in large automated tape silos with robotic arms on tracks. Data requested for processing from tape would be staged to disk, the job requesting the data would run, and then the data would be purged from disk after X hours/days.

It's easily done. Is there a business strategy behind it? Not sure.

Edit: I didn't answer your question. If I backup to tape and put the tape somewhere offline, I can't get access to it without a physical trip. I'm willing to trade access latency for lower cost, but I still want to move bits and not atoms.