As an industrial user with very high stakes in the operation and maintenance of complex systems like nuclear power plants, EDF has been engaged into simulation for many years. We feel that Exaflops software should not only be thought as a way of tackling daunting research problems but should also take into account the sometimes equally daunting requirements that stem from an industrial usage perspective. We do feel that, whatever the hard changes that will probably have to be made on various software aspects, we should not loose sight that continuity paths have also to be found in order to make those big changes acceptable and profitable to many. We identified in this paper what we think are priority research themes that could benefit of an international collaboration