There’s a reason why the Galaxy S6 has wireless charging and devices like the HTC One M9 do not. It’s metal. Current wireless charging methods are not compatible with materials like metal, but Qualcomm may have found a solution.
Qualcomm’s solution is based off the Rezence standard, which is different from the existing PMA and Qi standards. Their new upgrade operates at a different frequency that allows it to work with both metal and empty space. However, since it operates on magnetic resonance, so it’s not clear if it would work with ferrous metals and alloys, such as steel. But it would work with metal and titanium phones.
Samsung’s Electro-Mechanics subsidiary is part of the Wipower group, along with Qualcomm, and since the Galaxy S6 supports multiple wireless charging standards already, it could be possible that we could see this tech in devices at some future date. Then again, Rezence is from the Alliance for Wireless Power (A4WP) group, which is merging with PMA. Once a dominant wireless charging standard is sorted out, it remains to be seen what features will make it into consumer products.