It sounds like the certificates referenced in hardware are there forever. Is that true? What mechanism is in place to revoke and reissue new keys if one of them is compromised? Assuming that "normal people" will never upgrade their BIOS, doesn't this lead us to the same security problem we have now?

I guess the problem revolves around the signing key which is unlikely to make its way into the public. What if it does? Also, what happens when the certificates expire? Surely I'm either insane for asking these questions or they have already been addressed (or both)..