Personally I think limiting voltage is the key to bringing speed under control. Controlling motor winds, ESC technology etc etc is no where near as effective as dropping voltage.
The easiest way to do this is for the industry to move to LiFe batteries. This will drop the voltage by 10%+ and the batteries are safer. Stick with 1S for 1/12th and 2S for TC.
Would mean issues with shipping reduce, fire and the like due to incorrect handling reduce and in time - so will cost.
Not that I'm for it, but as for those suggesting controlling winds or boost etc is making it "stock" or too controlled - well, motor size (540) battery voltage (8.4V) and weight are already "control" - I agree we should have controls, but yes, they need to be smart and they need to not drive people to easily spend money elsewhere to try to win.
It's kind of funny that the cheapest classes to run in our hobby are actually the fastest ones.