Whats sort of amusing is that you can go back ten years and find pretty much the exact same discussion regarding discs happening in the MTB realm. The same arguments, the same reasons discs were bad/pointless, etc. Even into the 2000s, there were some shops that actually refused to stock disc-equipped bikes because "they were just a fad". At some point, discs went from being a bit of a luxury item to the market norm, and eventually even lightweight race bikes (the last big holdout for rim brakes) transitioned to discs. Nowadays, go into a bike shop and you'll have trouble finding a MTB for sale with anything but discs, and rim brakes are basically limited to vintage bikes and retro-grouches.
Now, I don't know if that will happen in the touring realm. I will say that I wouldn't be surprised to see some of the more popular touring bikes coming equipped with at least disc tabs on the frame and fork, to give people the option.