I see it like a professional sports team. Players have to deliver performance game after game. If they can't keep it up, they are traded or released, or their contract is not renewed. When they age-out, they either go into coaching, buy or start their own team, or move on to do something different entirely. They are taken off the field.
Applying this approach to a corporate workplace is controversial and I'd be interested in knowing what policies the legal department has put in place regarding employee agreements and termination processes to specifically accommodate Netflix' approach.