The 99600 is extremely charming and very elegant. Furthermore the only other brand, which put a pc and a minute repeater in a tonneau shape is Patek Philippe (if memory serves me well).
I think that a possible return of the Richeville is connected to the success of the Laureato and in general of GP in the next 2/3 years. If GP will become successful again we could probably see the return of this iconish model.
Thanks again for the exhaustive post! Best.