A WiFi dimmer would be a great addition to the range.
Yes, this would be amazing. Both in the S20 style and Sonos Touch style. Would replace majority of use-cases.
I agree a version with dimmer support would be fantastic. If you do this please make sure it will support incandescent, CFL and LED lighting.
This would beat most other modules (Zigbee, ZWave, KaKu, etc).
I am looking forward to the sonoff dimmer so I can control the fan speed because I've been using sonoff to automate home heating, circulating pumps and ventilation and this is the last thing I miss :)
Having everything in one application would be a great asset!