Wireless charging for all devices?

I'm just wondering if it would be technically possible or feasible for a third party to create a micro usb cap, that sits flush inside the micro usb charging port of phones without wireless charging, that enables them to wirelessly charge?

It makes sense that some devices are constructed from materials or component positioning that would perhaps inhibit or interfere with the charging, and maybe that the components required won't fit into the microusb port as a "cap" per se.

Something like this i'd happily pay between £15-30 for.