Much has changed since then, but unfortunately the laws physics and thermodynamics remain the same. If you had "non-combusting" tip thrusters then you'd need a much higher mass flow (due to depending soley on gas energy rather than converting temperature energy into gas energy in the nozzles). And this mass flow would have to come from the hub, piped inside the blades.
So you need ducting large enough to carry the mass flow and strong enough to take the pressure, and some way of getting all this high-pressure gas from the static part of the hub to the rotating part without any leaks.
Solutions invited...
PDR