I wonder, at what point will it be cheaper to kidnap and ransom those remote attestation engineers' families for key material than to work around those schemes with technical measures. Keeping in mind that people set up bot farms with physical phones just for attestation keys, it seems like tightening it all too much will just shift the balance towards the $5 wrench approach...
Well I guess AMD/Intel/Qualcomm/Infineon/Google people are at the greatest risk, with places like TSMC also in play. Infineon TPMs and smartcards in particular had so many flaws that I wonder if it already happened. Also, note that even if you don't have the keys you may still control the implementation, and potentially introduce flaws. Keep safe.
