That's a big ask. Hard to make them smaller and maintain performance without spending a fortune on something like carbon ceramic rotors and those might not be a great idea for off road use. Ultimately you need the mass of the rotor to dissipate heat.My wish is for a higher quality, better braking system with a smaller rotor, compact caliper, and stainless lines. It’d be really nice to be able to fit 16” rims without pretty of caliper clearance and no reduction in braking performance.