"They" did not go anywhere yet. This is a proposal, nothing more. It will take serious discussions over years to get this into C++.
Prominent figures already said they prefer safety profiles as a less intrusive and more C++ approach at conferences It will be fun to watch this and the other safety proposals going forward.
Yes, I should not have said "impossible": nothing is ever impossible to breach. All you can donis to make a breach more expensive to accomplish.
Those separate tpm chips are getting rare... most of the time they are build into the CPU (or firmware) nowadays. That makes sniffing harder, but probably opens other attack vectors.
Anyway: Using a TPM chip makes it more expensive to extract your keys than not using such a chip. So yoj win by using one.