It’s always (or never) too early to speculate on accident causes before NTSB comes out with a final report. The buzz on the Continental Q-400 crash in Buffalo, NY sure looks like icing and possibly tail plane icing.
What makes this plausible is that everything was going well until the gear and flaps were deployed. The gear probably isn’t much of an issue ( and you need it to land) but the flaps change the airflow/loading over the tail and that can upset the applecart. ASF has more detail on this in both the Aircraft Icing safety advisor and in the Weather Wise: Precipitation and Icing online course.
It’s way too early to predict all of the nuances that may have led to this tragedy but it will come out in due course. In my prior life at Cessna Aircraft Company, when flying FIKI equipped aircraft that had significant contamination, we were advised to go find a loooong runway, use no flaps and add about 20 knots to the final approach speed. The other point that has been made by many of you in past blogs is to not stay in the ice even with a big strong approved aircraft.