I think a direct air carpet cleaner/extractor would be aweso
Kirby could easily adapt the G-series for wet pickup. Since the handle is swappable, a special "handle" with the clean and dirty reservoirs (dirty routed from fan discharge, clean routed to floor nozzle with a high-pressure pump, piggybacked frrom the main supply cord) could be swapped in. Powered brush with a thinner nozzle to concenrate solution pickup, attached to the front. And, of course, the fan case and bearing assembly well-sealed and moisture resistant.
The base machine doesn't have to change much—mainly the front seal, bearing plate and bearing seal are all that would need to change on the power unit to make everything waterproof. Oh, and revert back to an easily removable plug so that a high-pressure spray pump could be piggybacked between the motor unit and supply cord.
After use, run the motor for 3-5 minutes to dry out the fan and fancase. A special moisture resistant HEPA cartridge could then be capped over the discharge to ensure that it exhausts clean air.
I think this would give most extractors—even some commercial grade models—a run for the money.