You will also have to contend and design for pretty high voltages as rpm is a function of volts in these motors. There are ways around this with big outrunner motors that turn slowly or with parallel windings. But as it is with the motors now used in electric experimental flight (often adapted from r/c), they're often running around 200V or more and that is a killer should you come in contact with it.
As mentioned, the brushless motors are not the problem from a certification standpoint, but the batteries and the power distribution is. We'll see how this develops in the coming years.