Large complex industrial Distributed Control Systems (DCS), e.g., power distribution systems, are expected to function for long time, up to 40 years. Therefore, besides having a long system verification phase for all subsystems, the design phase should consider various aspects when it comes to selection of which technologies to utilize when implementing such systems. In this paper, we study and investigate key challenges of using the Time Sensitive Networking (TSN) technology when it comes to design, maintenance and evolution of long life-span complex DCS. We also identify issues and challenges, and propose mitigation strategies for using the TSN technology in long-life system design. Our investigation and analysis shows that many of the TSN standards are in their evolution phase and may as a consequence be subject to different interpretations and implementations. Therefore, achieving a full capacity of using the TSN technology may not be possible, in particular when it comes to design of systems having an expected long life.