The boat long ago sailed on Mach/Hurd; there are probably better options in microkernel-land. There's Zircon, but Google laid off a bunch of the Fuchsia folks and has been pretty quite lately. QNX is still a thing, but closed source yadda yadda. Best hope there is probably the L4 family (seL4, et. al).
I would not be surprised at all if we end up with radically different OS architectures than the 1970's model we have today.
I would. Things tend to congregate into an ossified mess over time. Case in point: our current model is from the 1970s.
But it works, and it is unclear if alternative architectures are viable in practice.
If the new model is incompatible with the old, no one will invest in it. It's like you show people a warp drive and they just stare at you not understanding any of it because all they want is a better car.