I have a few reservations. "Wireless" charging is a bit of a misnomer, it's inductive charging. My phone has this capability, I set it down on a pad and it charges. The big limitation with this technology is proximity, a distance of more than a few milimeters between the charging surface and the device and you get no power. Knowing that I don't see how it would be applicable to bikes, and inductive charging is actually a relatively old technology, having existed since the late 1980's. It hasen't changed much since then and I haven't heard about any recent breakthroughs that would extend the range or effeciency.

As for charging it the old fashioned way, the SRAM group uses a seperate battery for each derailleur, that's two batteries to keep charged. My main concern is it dying in the middle of a ride, or getting wet.

Furthermore, I think it's safe to say cables are always going to exist on a bike for the braking system. If you have to have them anyway, why not have all of them.