Anecdotally, I've heard that there are ways to destructively image complete chips, and not just the layout but also the internal charge state. I believe the technique used femtosecond lasers. Of course that is also hearsay and I can't validate it.
My point is, as an interested layman, I don't know enough to trust this technology with my life - but it would be exactly useful if my life depended on keeping my secrets. So that contradiction kind of reduces its value for me.
I'm sure people with the required knowledge can properly evaluate these products, and for those people they are probably immensely useful.
Something I was told back when I was working around WikiLeaks is, "You can't make it impossible for them to get your goat, but you want to make it very, very expensive."
You'd probably be wrong. There are several consumer accessible chips (i.e. from Atmel that you can order on digikey) that use tamper-proof silicon where the very act of opening up the package to inspect the die destroys the private key data. Even civilian tamper-proof tech is extremely robust, using physical phenomena to protect the data instead of obfuscation.
That doesn't preclude someone with the resources of the NSA from figuring it out or backdooring the design but the resources needed to defeat tamper proof devices is orders of magnitude greater than those needed to use them and that gap is constantly growing.