Thank you for commenting, davidgdg
Reading your answer I think I have to explain in more detail the "use case"/ the scenario I have in mind for this method.
Let's say, it is intended to be a foolproof method for bitcoin cold-storage: I bought a bunch of bitcoins in the last months. It might be the case, that I loose interest in following bitcoin-news the next years (checking exchange-rates, legal status, security measures, new applications... whatever). So if in 5 years I discover that bitcoin is a huge thing then and my bitcoins are worth a fortune, i want to be able to redeem them. So, yes, the two problems you mentioned are exactly
the problem, but your requirement is not exactly the one I have in mind:
3. So supposedly what is required is some method of only having to remember some simple piece of information that then enables the owner to retrieve the passcode without having to write it down anywhere.
I want to have a method where I do not have to remember
any information at all (well, at least, not any
new information. I only use information I already know since my childhood). Using this information I do not have to remember, that the privateKey/passphrase is hidden in clown.jpg (which additionally might get lost in a HD-Crash) or in grannys birthday letter (which might get lost also). I can write the whole process on a piece of paper that I can put in my "finance"-folder on the shelf. And I can even give a copy of that paper to a good friend. Restoring the passphrase from the cloze text is easy for me but impossible for anyone else.
Re. 1. , if there are 10,000 English words, then choosing seven of them at random gives 1 * 10^28 combinations which should be enough for a few years yet even with terrahash asics.
Re. 2. a passcode is less obviously a private key than is a private key. So writing it down is less insecure than printing out and storing your private key (which is generally regarded as a very secure way to store BTC)
So IMHO the solutions are neat but they answer a problem that isn't really a problem.
Both answers you give here do require either remembering at least
some new information (you have to be able to recall it in 5 years) or you have to make sure that
nobody else gets to see your paper-wallet.