Let's say I own a $50,000 stable of rim brake equipped bikes and wheels.
Why would I replace them with $80,000 of disc brake equipped bikes?
The thought of filling up the landfills breaks my heart.
WRT to claims that discs have no aero disadvantage, my perusal of Tour Magazin results says otherwise. It is small, 2-6 watts but clearly there are cost(s) to changing to disc brakes. The only bike that I would like to have discs is on my recumbent because I hit very high speed, discs would make sense on that bike. Upgrade others? Not compelling.