My thanks to one and all who have contributed - it would seem I am quite able to leave my paper and text file private keys as they are for the time being.
Instead of thinking about the address, think of the private key. If you have the private key, your currencies will be backwarded compatibility for a long time.
Got it. The private keys are safe for now (anything could happen in the future).
I only put away a few hundred dollars worth of Bitcoin aside a few years ago in various places (Sorry for the vague nature of the amount or the locations). The price has been good to me, not enough to retire on, not yet at least. But, I know now there's not much likelihood the paper wallets will become incompatible before I might need to dip into those funds.