An autopsy will demonstrate nothing useful about her mental capability. Only a PET scan would have been useful for PVS - even if her skull is 3/4 empty the remainder may have been functioning just fine for adequate cognitive ability.
I am, however, interested in seeing what this says about the "broken bones" reports.
I don't think they're going to examine her broken bones. I don't expect anything to come out of this autopsy that doesn't look good for her murderers. If the medical examiner had intended to be open and honest, he wouldn't have refused an independent observation, which is just common courtesy and common practice.