At CNES, each new satellite simulation and testing system increases significantly processing requirements and real-time constraints. While mainstream systems allow adding almost unlimited computing resources, whenever there are stronger timing constraints, we arrive in a much unknown territory. To prepare the future, several R&D projects have been carried out that were focusing on related coming technological and programmatic evolutions that are considered enabling factors for the simulation and testing domain. Intelligent use of mainstream PC's, Linux, multi-core and HLA open up new ways of creating systems that can grow and be maintained for another 20 years.