Paper backups are never encrypted.  Part of the reason is to guarantee that you have a useful backup in X years when you need it -- and most people would forget the encryption passphrase by then and it would be like not having a backup at all.

The paper backup displays the "Wallet Version", which is all you need to know.  Even though I'm making a new wallet version now, I will still support the old one.  Even in 10 years, any prior version of Armory that ever worked will let you recover the wallet and print off a list of all your private keys.   Either way, the code to create the private keys from your paper backup should be a permanent part of Armory, even if Armory doesn't produce those wallets anymore, but because I promised you it would still work 10 years from now