"In fact, more than 100 million computers shipped to date have a TPM installed, and a number of RFPs from the Fortune 1000, as well as numerous government agencies, including the Department of Defense, explicitly require a TPM for all new computers."
"I believe there are varying methods to supply an alleged root-of-trust."
Well maybe (perhaps you could give some examples for the PC/Mobile space), but the thing that strikes a positive with me is we know a TPM in a PC can be a core root of trust (there are 500 million issued) and a SED can be a Core Root of Trust (MicroSoft thinks they will become the Go to standard for Encryption on PC's in the future). We know the equivalent of the TPM, the MTM is shipping or about to ship in mobile devices and they are the core root of trust in those devices, so whatever other methods you suggest are out there, I still like the SED/TPM/MTM combination as a predominant method. JMO