The biggest problem with turboprops from the pax point of view, based on discussions with people in airport lounges, is the noise and vibration with the derivative perception that turboprops are less safe, as well as being less comfortable. I know when paxing I avoid a seat in the rotation plane of the prop and to a lesser extent the engines. Seems this may take some work to overcome, if for no other reasons than so many years were spent selling the punters on the smooth, quiet jet service.
Maybe the place where there is more to be made on this is the all cargo carriers. FEDEX launched on the Cessna Caravan, wonder what the economics are? When FEDEX's replacement for MD-11s etc is a turboprop we'll know the time has come (maybe)