It's something which seems crucial to me for reaching mass adoption (in addition to scalabilty of course...).
Already on this forum there is a shitload of people losing their Bitcoins by forgetting passphrases, the private keys, the dat file etc...
So I would like to know what technological solutions could be proposed for this problem.

To make a comparison, a lot of people are forgetting their credit card code (even if it's only 4 digits...) or losing the card and the centralized solution to this is the bank providing new card/code.

Which decentralized solutions to this problems could you think of?