According to most here, just buy Bitcoin and keep it in your wallet.

So find an exchange that's still functioning, give them your money for some tokens, and then extract them onto a thumbdrive.

Fine.

Then a few years from now when you need some cash and want to sell, find an exchange that still exists, upload some tokens from your (hopefully) still working thumb drive, and then hope further that you can exchange them back into cash...

That about right?