While I tentatively agree with what you've said, I'll add that if someone breaks SHA-256 or SHA-512 anytime soon, all three. Supposedly we'll see attacks against hardware wallets this year at Defcon or Blackhat. I'd buy a Nano S anyway, but I would keep it in my safety deposit box or safe, or in a highly secure location because it's going to be physical attacks. Someone might've come up with ways to crack mnemonics faster but that's always been an issue for brainwallets and always will be, whether 3, 6, 12, or 24 words. I do like the plausible deniability feature of the Nano S, but it may be pointless if a great attack method comes out at one of the hacking conventions this year.

To flesh it out for him, nothing is stored on your hardware wallet that isn't corresponded with in the blockchain. Your wallet isn't holding your money, it's more like a key to your safety deposit box. You personally can be held hostage for it, and it may be that this year proves that it's physically vulnerable itself. I like the Ledger Nano S over the current alternatives, but if you're looking for long-term cold storage I'd buy more than one and have some very secret hiding place that only the Executor of your Last Will and Testament will have access to.