The most reliable automatic way of forgetting your Bitcoin private keys for 7 years

The problem with ntimelock is that you have to keep your raw data for the transaction, and also you must destroy your private key from which you've sent the transaction. You theoretically still have opportunity to double-spend your ntimelocked funds if you haven't destroyed your private key from the wallet from which you've sent ntimelocked funds, because inputs are still belonging to that wallet. Transaction will occur only on the event when nTimeLock raw data will be executed after the specified ntimelock.

I'm think the digital time capsule is greater, because its easier to setup than nTimeLock, even though nTimeLock would be better solution.

The greatest independent solution of course would be combining 2 methods: - Digital Time Capsule - e.g. ability to bruteforce during 1 year using reasonable amount of hardware. That's for sender privatekey. You have to create around 100 private key pairs upfront, so that you could slowly use them to deposit funds there, then destroying those private keys, relying only on bruteforce data and ntimelock raw transactions dumps saved to be executed on time. + nTimeLock itself in combination with Digital Time Capsule which applies to sender wallet. And all of the nTimeLock raw transactions are directed to one wallet, private keys of which won't be stolen.

So, you will have 100 sender wallets with Time Capsule key pairs which you will destroy after usage. Also you will have accessible not destroyed very well known private key from your recipient wallet, where you'll expect to receive funds after ntimelock event, once you'll push raw transaction data into the Bitcoin network.

I'm actively studying this topic right now, once I'll come up with solution, I think I will open a web-site helping others to use this open techniques to save their Bitcoins.