Can a turbofan maintain torque when spinning fast? I assume turbofan fan rpm could be increased only when:


Using most modern jet engines (Airbus A380 and the Boeing B747-800)
Using a magnetic gearbox which can handle more torque dor the same weight
Fan and compressor blades are reinforced
Design muffles and silences the fan sonic boom
Engine is designed to prevent a flame out.


Assuming the problems above are solved, and one was able to redesign the fan and compressor blades to be efficient at 10 times their current rpm, without changing the power rating:


Would the engine have enough torque and power to spin the fan at cruise altitude?
What would be the effect on thrust?
An initial thought is that at 10X the RPM, it is likely that the blades would be well into Mach numbers, which would have a negative effect on power requirements (that is substantially more torque in particular) to spin the fan, and more importantly the fan would not be effective at those speeds.  There would likely be blade damage as well from the loading.

However this is a rather hypothetical question, where if an engine were developed to do this, there would be other trades to be made in the design of an engine. Changing just one part of a system such as a jet engine, usually does not favorably alter the overall performance.