Itead Sonoff RF WiFi & 433MHz switch: Identifying an unknown chip on the 433MHz card
The QFN Package is the BB10-F2G microcontroller from silicon labs. The other chip, as you've identified, is just an ASK receiver. The microcontroller is decoding the output into commands. It doesn't really seem like there's anything else on the card. The crystal is there to allow accurate timing for decoding the radio signal.

You can probably reprogram this chip using the Simplicity Studio tool.