Print it out and lock it in a safe deposit box at the bank. If you can't print the material, put it on two flash drives or disks and put them in the box. Occasionally verify the drives or transfer to new media over time.
There aren't many alternatives that are both safer and more practical for the average person for long time scales. You probably don't want to spend a lot to keep 2GB of personal files stored. Any tech company or cloud storage solution is less likely to still be operating and still be offering the same storage services on decade scales than a bank.
A safe in a location other than a bank, like your home, is more likely to be stolen. In your home, a burglar can force you to open the safe. There's much lower chance of that happening at the bank.
Should an online service fail, you may lose your stored data without notice or recourse. A company can be raided and their servers pulled out of racks by the FBI because of something just one user of the service did. The FBI is less likely to show up at a bank and take other customers' safe deposit boxes.
Should a bank with safe deposit boxes fail, you are guaranteed access to your possessions by the FDIC. Either the FDIC will arrange for your branch to be taken over by another bank, or if no other bank wants to take it over, they will arrange to return the contents of your box to you. This happens immediately: the FDIC guarantees you will have access to your safe deposit box at a failed bank the very next business day should you want it.
I expect the federal government to still be around in 60 years. If they end the FDIC program, you can re-evaluate at that point.
