I think we can be pretty sure that al Fayed is using this inquest to try to avoid mentally having to take the responsibility for the death of his son. The reason for all the 'witnesses' is to try to prove beyond a reasonable doubt, that as Diana was probably not intending to marry Dodi and was not pregnant, there would have been no reason (to a twisted mind playing the race/religion card) for Philip to arrange to have her killed. let's face it she has caused as much, if not more damage and division with her death than if she had lived. The royals and their advisors are not silly, although they couldn't have foreseen the disgraceful exhibition in London, if they had wanted to be rid of her, they would have, IMO, done so when the marriage had clearly broken down, before the Morton book or at the very least before the Panorama interview.
I believe a new offense has been brought in, one of corporate manslaughter, but it will not be retrospective and is not a path the royals or government are likely to take.