It's widely known that rotors demagnetize if they're overheated, but doesn't that raise the motor RPM as a result?
Here's a comparison of rotors from Trinity for reference: https://www.teamtrinity.com/assets/i...rt-updated.jpg

Generally, the lower-gauss models are listed as "high RPM". Can't you just increase gearing as the rotor weakens, to get torque back as RPMs rise?
Naturally, this approach would fall apart if the magnet went all the way to 0.... but if it's just an incremental degradation from say 1700 to 1500 gauss, I wonder what the difference really is to total power, and whether it's worth replacing the rotor.

Less rotor strength = less available power aka wattage. This is because you aren't changing other aspects of the motor to also increase wattage. So the same turns of wire, but a less powerful magnet means the motor makes less power. Yes if the strength/power falls enough you should gear down and let the motor rev. But over all the highest strength rotor is best. Thats why all the latest motors are going to much much stronger and longer rotors.