In the 2000s we spoke about distributed operating systems (Inferno, etc.). That's where systems research seemed to be headed, yet that never really took off. But maybe we're revisiting the concept now, just coming down from the layer above (e.g. application data types) instead of trying to rethink the OS.
I work on this [1], it kinda looks like systems software, and it doesn't feel stagnant. But then, nobody uses it (yet - I hope).
And there's a plethora of similar ideas (DAT, OrbitDB, etc.).