Funny thing about the "on package bios", "which takes 30 minutes to reset".
I know as a fact that the bios on these systems is not located on chip, but on the motherboard as usual. It would be impossible to have the bios located inside the CPU, since different boards require different code depending on their configuration. The bios contains initialization code & firmwares for the external peripherals, such as storage, network, audio, etc controllers and in some cases programming parameters for the VRM controller. Not to mention that nowdays most of the ODMs have proprietary functions in their bioses (such as tuning features).
So unless AMD plans to pre-program the CPUs to work only in a specific board model, or alternatively the ODMs plan to bundle the CPUs with their boards... well, make your own conclusions.
Zeppelin uses a new AGESA core version, but the basic layout & functionality is still the same as on previous platforms. Most, if not all boards will be using Aptio V bios from AMI.
Zeppelin does have a tiny ROM "on die", however it doesn't store anything bios related and there certainly is no need ever to "reset" it.
Also the SMU stands for "System Management Unit", it is not the abbreviation for AMD's SMT implementation like the "source" claims it to be. SMU is the "master of the puppets" on recent GPU ASICs and APUs / SoCs since Trinity. You've seen me talking plenty about the SMU in the past.
At least for now the multithreading implementation goes by it's original abbreviation, SMT.