Is Linux a repeatable phenomenon? Is there a college student today whose hobby OS can snowball into such a dominant technology? If Linux started in 2011, I wonder what design decisions would have Linus made differently. The Innovator's Dilemma suggests that a disruptive technology replace a dominant standard by working bottom-up: specialize in a corner of the market that is too small or unprofitable to be of interest…
Linux lacks in real-time features. That could be an angle to get in a new operating systems.
There's a saying that Unix stopped serious research into operating systems. Whenever somebody writes a new system nowadays, one of the first things they port is the Unix infrastructure.