If Intel wants people to stop using SGX, they should have intentionally leaked the master attestation key for it. Then the only loser would be the MAFIAA, instead of all of the innocent customers who bought Blu-rays.
I don't know, for instance, if password wallets use it for protecting their data when they are loaded, but that would lead to pretty bad consequences.
If your hardware enhanced wallet relies on SGX, It sounds it is defected as it shouldn't be readable after first write at first place.
And why did you think you need signing key for SGX to extract info from it? You only need the decrypt key (Which is already been pwned). Lack of signing key only prevent you from running random program in SGX but not decrypt existing one.