The FAA does not think they will ever last over 3 years, hence the reason there is not a renewal process for registration. They estimate the lifespan of 1 year for 90% of sUAS.
That was a good assumption and proven case leading up to this point, but that is because the use of multirotors is just graduating past infancy. The planes and helis I have had over the years have lasted 5-10 years before I replaced them, but there was a lot less as far electronics go. The reason the upgrade or replacement cycle has been so high on this type of craft is because the technology is still coming into place. Better gyroscopes and accelerometers, better antennas for communication and positioning, better motors and propellers, better battery technology, better cameras and gimbal systems.
Looking at the technology and advances in just the past 5 years, THAT is why the replacement cycle is seen as 1 year...but what would have to be on the next generation to make you upgrade? Some of us just upgrade because we want the latest or the newest shiny toy, but what new FEATURE would make us upgrade sooner? Longer battery life, for sure. Better camera, maybe. Longer range, possibly. Faster and more efficient motors, likely. Higher quality live video feed, I suppose. Something we never even thought of, definitely!