There are three primary leaders in the marketplace currently with slightly different approaches.
PMA on the other hand has been focusing on branding and developing a pull strategy by trying to build momentum through consumers. They recently gained significant traction when they partnered with Starbucks on launching a test for PMA chargers in numerous stores. With virtually no devices actually developed that will work on PMA chargers, we're not sure how successful this will be. There are some limited offerings of cell phone cases that work with PMA. In addition, most major manufacturers such as Samsung have joined all the standards boards to cover themselves. They have yet to launch product offering with PMA though. Starbucks also serves on the board so this relationship should likely grow.
We haven't ruled out A4WP yet but they are well behind Qi and PMA in terms of adoption. Intel recently joined which gives the organization body significant credibility and greater resources.
What does the future hold?
If we had to place bets, we believe that there is enough momentum with Qi that they will emerge the leader. This is such a new technology that consumers are confused by the standards. If someone takes their Qi Receiver based phone to a Starbucks with PMA transmitter, it won't work.
There is also an interesting development taking place with Induction Charging module and chip set manufacturers. We are seeing developments of transmitter modules that are compatible with both Qi and PMA. These chip sets should start entering the market place early 2014. While this helps the consumer, we're not sure if will speed up the adoption of a clear standard or just blur the lines longer. We are not seeing dual mode receiver chips yet but would not be surprised if those were in the works as well.
As for resonance charging... we actually feel this may be able to co-exist with induction charging. There are enough distinct differences between the two technologies. As time goes on and efficiency increases, resonance charging could slowly start to push out induction. But we are years away from that happening.
There is a wildcard to all of this... The elephant in the room for all this standards discussion is, "what will Apple do?" They have filed several patents related to this topic. One is based on induction charging using a battery smartcover. The other is based on resonance charging from a desktop computer to keep accessories such as a keyboard and mouse charged. No one is certain if Apple will adopt one of these standards or if they will create their own version. If so, that could completely change the game due to their enormous user base. If iPhone 6 came out with wireless charging capabilities, that is likely to be the standard for this nascent technology.