If I understand the OP correctly they seem to be asking for some way for the 'rightful owner' of a private key, who then has it stolen, to have some sort of fallback method of moving the coins without the private key.

For this to work there needs to be some sort of 'proof of identity' that the rightful owner could provide in lieu of the private key. In other words they need to have...

another private key.

This seems doable to me. Take whatever existing coins you have and transfer them to a new address by means of a 1-of-2 multisig transaction. Then, you need some way of separating the two private keys into two separate files (wallets or whatever). That might be the tricky bit - I've never done multisig transactions myself so I don't know how the major wallets implement them. You might have to 'hand-craft' a transaction. Finally you need to keep the two private keys very, very separate - like, one on your laptop in a wallet.dat, the other on some laminated paper in the household safe.

Then, when your laptop gets nicked, you use the key in the safe to move the coins. And vice-versa if the safe gets broken into. Of course there are failure-modes:
1) If BOTH your laptop and your safe get nicked you're effed.
2) If the thief spends the coins before you realise they're gone, you're effed.
3) You can't do all this retroactively. If the thief's already stolen your coins protected with a single private key, there's nothing you can do about that NOW, just do the multisig for your future coins.