It seems that a fresh wallet.dat is around 140kB, but AFAIK it contains already 100 keys. In order to secure an offline wallet, I see two very distinct threats:
1- getting the wallet stolen
2- losing the wallet
The easiest way to address No1 is to bring the wallet offline. Yet, suddenly, it becomes a lot harder to end-up with super-durable storage.
At 140kB, printing the wallet is rather cumbersome, but assuming that it could be brought down to 1.4kB (with only 1 key), it would be much easier to backup, possibly through super-naive Base64 encoding combined with plain text print (and OCR for recovery, with the option of doing it the manual way if OCR fails for whatever reason).
Are my numbers correct? Any thoughts in providing such an option to produce such thin wallets for the sole purpose of offline saving?